Steps to replicate the issue:

Compare this dewiki page in Vector Legacy and in Vector 2022. The page contained an unbalanced '' in the section title.

What happens?
In Vector Legacy, there is no immediate effect. In Vector 2022 however, the entire page content is seemingly wrapped inside a <i></i> and everything is italicised. Also, the TOC is moved to the bottom.

What should have happened instead?
Vector 2022 should handle such mistakes like Vector Legacy.