I fully agree that this is what's happening. I'm quite convinced after about a year of using all these tools via the "pro" plans that all these companies are throttling their models in sophisticated ways that have a poorly understood but significant impact on quality and consistency.

Gpt-5.1-* are fully nerfed for me at the moment. Maybe they're giving others the real juice but they're not giving it to me. Gpt-5-* gave me quite good results 2 weeks ago, now I'm just getting incoherent crap at 20 minute intervals.

Maybe I should just start paying via tokens for a hopefully more consistent experience.