Yes, it should be banned. To the question of "how"How do we identify those posts?", it should be considered that this problem is not new or unique to SOStack Overflow. Plagiarism is a concern that spans broadly. An answer found in academia is to copy/paste answers back into ChatGPT and see if it will respondresponds to it as a continuation of the conversationa conversation; if it does, flaggingthen flag it as AI-generated.
This is a potential technique, and one that scales. Multiple suggestions here implyingimply that "you can tell it by looking at it", which isn't all that helpful because we can't expect people to reliably keep up with the potentially exponential flow of spam answers.