- ChatGPT’s hidden backup model just got smarter and it’s a stealth upgrade that happens in the background
- OpenAI also announced a new $100 Pro plan, shaking up who gets access to its best tools
- The changes show OpenAI is making ChatGPT more tiered and more complex behind the scenes
OpenAI just made two big changes to ChatGPT, but only one of them is obvious. The big news is that there’s now a new $100 Pro plan that comes in cheaper than its $200 Pro option, but gives you more access to Codex, OpenAI's programming tool, than a Plus user would get.
The second change is introducing a new ChatGPT’s fallback model, for when you’ve hit your rate limits on ChatGPT-5.3 Instant. The new model is called ChatGPT-5.3 Instant Mini, and you can’t select it in the model picker, since it's what you default to when you’ve hit your rate limits.
Taken together, the new changes show OpenAI is reshaping both the free-flow experience of using ChatGPT and the way it packages higher-end access.
The hidden upgrade you won’t notice
GPT-5 Instant Mini replaces ChatGPT-5.3 Instant as the fallback model you get after you’ve hit your GPT-5.3 Instant limits, which will depend on what plan you’re on. Before the new release, you were defaulting to ChatGPT-5 mini. OpenAI claims that ChatGPT-5.3 Instant Mini outperforms GPT-5 Instant Mini across a range of different use cases.
“Compared with GPT-5 Instant Mini, GPT-5.3 Instant Mini feels more natural in conversation, with stronger writing and contextual awareness throughout chat”, OpenAI said in the release notes for ChatGPT-5.3 Instant Mini.
The change is happening behind the scenes, but even if this only affects the “overflow” experience, it shows that this is where a lot of regular users end up. It’s the Pro users who will be less likely to be affected, since they have much higher usage rates.
The new $100 Pro tier
At the same time, OpenAI is introducing a new $100/month Pro tier (£89 in the UK, AU price to be determined) aimed at longer, high-intensity Codex sessions. It includes unlimited access to GPT-5.4, access to GPT-5.4 Pro, and temporary up to 10x mode Codex usage than the Plus tier.
What’s confusing is that the $200/month Pro plan still exists, so now there are two plans for ChatGPT called “Pro”. It's easiest to think of the $100/month plan as a middle tier between Plus and the more expensive Pro option.
OpenAI describes the $100/month Pro plan as having 5x more usage than the Plus tier, while the $200/month plan has 20x more usage. Aside from that, everything between the two plans seems the same.
What changes for Plus users
There is also one small change for $20/month Plus users. The temporary Codex promotion on Plus is ending, so OpenAI is rebalancing Plus usage to support more sessions across the week, rather than for longer, high-intensity sessions on a single day.
This is effectively OpenAI redefining what Plus is for: lighter, steadier everyday use rather than heavy-duty bursts. At the same time, it's introducing a new middle tier in the hope that those people using ChatGPT Plus for coding will upgrade.
