Related patch is not solving original problem of this task. Additional patch is required.

I was debuging this scenario, figured out what is wrong, but I am not sure, what parsoid should in this scenario do. Problem is like this:

Note for release of 1.45.0-wmf.19: If Parsoid will be rollback into v0.22.0-a21, then rollback in core is required up to patch https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1188409.

Documentation of lint: https://www.mediawiki.org/wiki/Help:Lint_errors/template-arg-in-extension-tag

Possible replication:

Template:Ta

<includeonly>{|
<div>
</includeonly>

Template:Tb

<includeonly>
</div>|}
</includeonly>

Page

{{Ta}}
řaa
<table>
<tr><td>
a
</td></tr>
</table>
{{Tb}}

Letter ř in this case can be replaced with any 2 byte utf-8 character.
Error stack trace: