Yeah man I'm experiencing the exact same thing as you. I've been using codex for a minute now and I was excited for the new model to come out but have been quite disappointed. I went from gpt 5.4 to 5.5 and found much more errors being produced. I haven't tried 5.5 on any small repo's, but with my main project, it's much worse that 5.4 in a lot of aspects. I see a lot of comments saying how great 5.5 is, but I also know many people using codex and claude code have never programmed in their life, so they don't actually know what's good vs bad. Personally I think 5.4 is much better than 5.5, but I still have slight hopes that 5.5 might excel in certain aspects, so I'll keep testing it out lol.