Steps to replicate the issue (include links if applicable):

• In the first comment of a thread, write wikitext heading syntaxes that does not emit headings (e.g. with {{void}} or the match-and-replace codes in zh:{{比較條文}})
• Use the "Reply to Section" feature.
• Check the diff in source code.

What happens?: The comment is inserted before the first "fake headings", for example:

== The Thread ==
Ordinary contents.
{{void|1=
<!-- [COMMENT WRONGLY INSERTED HERE] -->
=== I am hidden! ===
Other contents that will never be seen.
}}
And the end. [[User:Example|Example]] 2026-06-11 03:21
: <!-- [COMMENT SHOULD BE HERE INSTEAD] -->

See for example zh:Special:Diff/93018910 and zh:Special:Diff/93021711.

What should have happened instead?: The comment should be placed below the whole comment.