Now with AI, at least after a ~year of using AI for development, things haven't changed in terms of responsibility: my commits still have my name on them, and people will come to me with questions. If I cannot answer the question because I forgot the code or never wrote it in the first place, I will sit down and figure out.
As for the reviewer, I never saw anyone being grilled for stamping buggy code. People make mistakes all the time, including when reviewing someone's code. Code reviews are nice to have and catch real issues, but it's naive to think that they could protect from code breakage, regardless if it's post-AI or not.