I've been using GPT-5.1-thinking for the last week or so, it's been horrendous. It does not spend as much time thinking as GPT-5 does, and the results are significantly worse (e.g. obvious mistakes) and less technical. I suspect this is to save on inference compute.
I've temporarily switched back to o3, thankfully that model is still in the switcher.
Double checked when the model started getting worse, and realized I was exaggerating a little bit on the timeframe. November 5th is when it got worse for me. (1 week in AI feels like a month..)
Was there a (hidden) rollout for people using GPT-5-thinking? If not, I have been entirely mistaken.
I've temporarily switched back to o3, thankfully that model is still in the switcher.
edit: s/month/week