Recently, there are a lot of new pseudonymous users with a peculiar pattern of posts: only answers, no questions, in lots of widely differing areas of mathematics (where it is unlikely that one random pseudonymous person is expert in all of them), posted in quick succession, which often look OK superficially (including MathJax an all), but actually miss some important step or make unwarranted assumptions or abuse notation in odd ways. I strongly suspect that these users are using AI tools to write their answers.
What should one do about these cases? (Especially if some answers are actually not that bad and get upvotes and accepts?)