The previous comment is definitely malformed (it has a {{tree start}} and {{tree end}} template split across two <dd> nodes). One for the parsing team.

This is a known issue with Parsoid, where editing pages that contain fostered content (*) will result in corrupted wikitext (T240280). The reply tool is supposed to prevent this by refusing to edit affected pages (T246481).

You can see this in action here: Talk:Fostered – if you click "reply", you'll just get an error message, because of the "fostered" error visible at Special:LintErrors?pagename=Talk:Fostered.

Apparently this doesn't work for Wikipedia:互助客栈/方针 – even though the page contains fostered content, there isn't a "fostered" error at Special:LintErrors?pagename=Wikipedia:互助客栈/方针.

(*) "Fostered content" is the name for some kinds of invalid HTML markup, e.g. text or markup directly inside a <table> node rather than inside a <td> node. This causes the parser to pull out the text or markup in front of the table, which is called "fostering". https://www.mediawiki.org/wiki/Help:Lint_errors/fostered