ChatGPT has been silently routing Pro to mini for several months

Using $200/month OpenAI's ChatGPT Pro(not lite), ChatGPT has an issue where some Pro model sessions responded like a mini model, or were routed into one, even when Pro was selected in model picker. This is not normal, never been documented, and has no visual cue whether it's affected or not. My finding relies on analyzing "frozen/static" chat metadata content ( resolved_model_slug ) rather than potentially hallucinated model outputs or chat responses.

I contacted support for two months [img1] but received only general/simple responses. Users paying for the $200 plan expect research-grade intelligence, not a same model offered to unpaid users. I publicly ask OpenAI to explain this issue.

This happened next day after I subscribed to the $200/month ChatGPT Pro plan [1] . While working as usual, the responses felt different. I can understand OpenAI's model performance can be inconsistent, but this change was too extreme to ignore.

The model's outputs fell far short of an expert or researcher quality, with the reasoning and thinking time significantly faster than normal (by dozens of times). Consequently, the performance was significantly below what is typically expected from the Pro model.

After noticing this, I asked, "What model are you?" It identified itself as a completely different model: "GPT-5 mini."

At first, I thought this was a model hallucination. Since there was no technical report for the Pro model, I thought its internal system might use mini models in some cases.

However, my suspicion increased after comparing different clients logged into the same account. Some clients that had remained logged in for a long time(still not exact, some clients were affected too) still behaved as expected from the Pro model. New logins and other clients showed invalid behavior. This must not simply a response varied with prompt complexity (like simple prompt goes to a simpler model). Both the web and Android clients were affected just in case.

The affected Pro sessions showed the following behavior:

I then investigated ChatGPT data exports and backend network responses. Based on an early reply from customer support, every chat in which the assistant identified itself as GPT-5 mini contained i-cot in the resolved_model_slug metadata property. About a month later, another colleague researcher reported a similar case. In that case, that property was set to gpt-5-5-mini .

While investigating that report, I also found a growing number of similar issue reports on social media recently [reports] . Thus I decided to write about this issue.

Customer support made this issue even more frustrating. I contacted support for about two months [img1] . The replies focused on general explanations, such as model hallucinations or clearing the browser cache. I never received any explainer, actual investigation results, or clear solution. Attempts to contact relevant OpenAI employees through X also received no response [img2] .

What I consider most important about this issue is transparency . People pay $200 per month not only for Codex, but also for research-grade reasoning. Yet this behavior continued without any clear notice in the UI or by email. There was no visible indication/cue that something had changed. The issue might not be limited to Pro users; Pro Lite and Business accounts have fewer quotas. Users have no reliable way to confirm whether they are receiving the service they paid for. I was affected for several days. For that period, the money was effectively wasted away.

AI products are no longer toys nowadays. They are becoming essential tools for research, development, writing, analysis, and decision-making. Users of expensive services expect more than better answers; they also expect predictable service like usual. When a model's behavior suddenly changes and performance becomes worse, the issue is no longer just performance. It becomes a matter of trust .

I am not claiming that these observations prove every part of my point. However, OpenAI has provided no explanation at all.

Users have every right to question whether they are receiving the service they paid for. When a provider stays silent or repeats useless answers, users lose trust in that provider.

I'm not asking OpenAI to disclose confidential internal information. If this was a bug, respond that it was a bug. If it was part of an abuse-prevention or rate-limit policy, explain that effectively. If fallback routing exists, explain when it occurs, address how it appears in the UI, and explain what level of service is guaranteed to paying users. Customer support never gave me any information about any of this.

Since this article is solely focused for scientists/researchers/developers , I still have a lot of stories to talk about. So I might publish more articles when they do not address this. Thank you to everyone who read this long and low effort post.

Computer engineering undergraduate student in South Korea. I have some LLM-like knowledge through discussions with NLP doctoral student, AI (mostly vision, but work for all domains) researcher who studied neuroscience on their own, and industry professionals. I do research on computer graphics, desktop Linux, and software engineering.

The following ChatGPT shared chat sample links are available:

At the time of writing, there are two objective ways to check:

In both cases, check the prop value near resolved_model_slug . Expects i-cot or gpt-5-5-mini or similar. The first method is strongly recommended. The only advantage of the second method is that it does not require login.

While it was possible before, requesting a data dump export and inspecting resolved_model_slug is unavailable now. The property seems to have been removed from exports recently. A comparison is available in this GitHub Gist link .

[1] ChatGPT Plan | Pro. https://chatgpt.com/plans/pro/ visited 2026-07-30 (archived https://archive.md/H0nR2)

Disclaimer: Some portion of texts are not exact; some may truncated, machine-translated etc.

@paulscu1 (06-14): Just tried OpenAI’s web UI, I’m shocked at just how bad the model routing is. I’m paying $100 a month, and I can’t get more than one reliable response from 5.5 pro before I start getting routed to like 5.3 mini. It’s absurd product design, I will pay more, just please please fix this it doesn’t work X Post

@Mortid_X (06-18): ChatGpt Pro extended 5.5 > GPT-5.3-mini model. This is some kind of bug. On my phone, everything works fine for me. I hope the @OpenAI team fixes this bug. Watch the video for proof: [video] X Post

@ludicrouslytrue (07-21): My web chat silently falls back to 5.5 mini? I'm on the 20x Pro plan @thsottiaux I thought codex and web limits weren't shared, oh well. [video] X Post

@sizumita (07-23): Why is it a 5.5-mini when it's a Pro model? X Post

@_machi47 (07-24): across all of my GPT chats on the Pro plan, when using GPT 5.6 Sol Pro, it routes to GPT 5.5 mini. What is happening @thsottiaux ???? no notices of degredation on the app itself. shows pro level, but does not reason at all, jus instantly spews garbage? X Post

@q8jx_ (07-24): does your gpt 5.6 pro say it's gpt 5.5 mini too? X Post

@RealWilliamHsu (07-24): You guys doing great but ChatGPT with 5.6 Pro returned replies using GPT 5.5-mini, how's that a genuine reply to the users?? X Post

@kumataro_x (07-26): @OpenAI Support rejected my refund request, saying it could not confirm that my Pro requests were handled by GPT-5.5 mini. I now have structured data returned by ChatGPT's own web backend showing exactly why this requires an engineering review. I selected Pro. The conversation data shows: `default_model_slug: gpt-5-6-pro` But two separate requests show: `resolved_model_slug: gpt-5-5-mini` This is machine-readable metadata—not a guess based on response speed or AI self-identification. I obtained the JSON directly from the response payload in my browser's DevTools Network panel while loading the original ChatGPT conversation. The conversation ID in the page URL exactly matches the JSON. I also preserved the original file and its SHA-256 hash. OpenAI's Help Center says Pro is powered by GPT-5.6 Sol Pro. It documents GPT-5.5 Instant mini as an Instant-limit fallback—not as a fallback for selected Pro requests. @OpenAI, please explain what `resolved_model_slug` means and check the actual serving model for my two request IDs. If Pro served them, why did your backend return mini? If mini served them, acknowledge the routing issue and reconsider the refund. X Post

@whatfordinner12 (07-28): I pay $100/month for ChatGPT Pro. The UI showed GPT-5.6 Pro. Pro quota was charged. But the request was routed to GPT-5.5-mini. But after I submitted screenshots, chat links, and quota evidence, Support twice dismissed it as “AI hallucination.” (1/5) X Post

@TuringMeme (07-28): I’m a ChatGPT Pro user. Today I noticed that selecting GPT-5.5 Pro automatically switched my conversations to GPT-5.5 Mini. Support explained that Mini is the fallback after reaching the Pro usage limit. I understand having a fallback model, but the problem is: the quality difference is obvious, and there is no clear indication of when Pro access will be restored. Please show the limit status and reset time. Transparency matters for Pro users.

@zhihe_md (07-29): I am extremely dissatisfied with ChatGPT’s current risk-control and model-routing system. I subscribe to the 20× Pro plan, yet I previously used fewer than 2 pro requests per day on average, and my Codex usage rarely exceeded 30% of the available quota. My overall usage has been modest, with no apparent indication of abuse or abnormal activity. Despite this, all of my GPT-5.6 Sol Pro requests are now being routed to GPT-5.5 Mini. In practice, this means that the main high-performance model included in my subscription is no longer available to me. The system has provided no clear explanation, no estimated duration for the restriction, and no meaningful appeal or review process. I paid for a higher-tier Pro subscription, but my access has been silently downgraded despite normal and limited usage. This opaque and indiscriminate risk-control mechanism seriously undermines the value of the subscription and my trust in the advertised Pro benefits. Please conduct a manual review of my account, explain the specific reason for this restriction, and restore access to the models and service level included with my subscription. X Post

"5.6 pro model has been automatically downgraded and routed to the 5.5 mini model since its release" (07-23, 9 users) OpenAI Developer Community Post

"Pro subscription routing to GPT-5.3 Mini for 48+ hours — no reset timer visible" (06-17, 32 users) OpenAI Developer Community Post

u/ilsubyeega (06-22): P.S.: The Pro model quietly redirects to GPT-mini based model. $200/month Reddit Post

u/immortalsol (06-18): I am being silently rerouted to GPT-5.3 mini when using Pro Extended mode on ChatGPT webapp. What the hel lis going on? only started happening today. Reddit Post

u/TrainingEngine1 (05-24): My 20x Pro Plan has every message reverted to 5-Mini and OpenAI refuses to help. [content deleted] Reddit Post

u/Pleasant-Contact-556 (2025-05-02): What are i-cot and i-mini-m? I got rate-limited on my pro subscription. It happens occasionally for who knows what reason, and when it does you can tell because all of the CoT models route to something.. lesser.. Reddit Post