@RhinosF1 mentioned that I should be able to manually add the four tildes (~~~~) as my signature, which I hadn't initially considered. It's less ideal, as I do feel this shouldn't be too difficult to resolve this bug by having the extension check for an unclosed <small> tag and close any <small> tags present in the reply, but is still an acceptable workaround; however, upon further testing, the four tildes (~~~~) is simply added to the auto-added signature that the extension adds. So, as a secondary or in addition to fix, the extension should check for any four tildes already in the reply and, if present, not add a signature.

This will be fixed by the new indented comment syntax (T230683), which should create a per-comment context from which unbalanced tags can't escape.

One could round-trip the wikitext through Parsoid to ensure balanced syntax, but this is counter to what we have tried to do so far with the wikitext mode, which is that should preserve the wikitext as-typed by the user as much as possible.

In T267663#6617075, @dmehus wrote:

@RhinosF1 mentioned that I should be able to manually add the four tildes (~~~~) as my signature, which I hadn't initially considered. It's less ideal, as I do feel this shouldn't be too difficult to resolve this bug by having the extension check for an unclosed <small> tag and close any <small> tags present in the reply, but is still an acceptable workaround; however, upon further testing, the four tildes (~~~~) is simply added to the auto-added signature that the extension adds. So, as a secondary or in addition to fix, the extension should check for any four tildes already in the reply and, if present, not add a signature.

Task T268558 is another request to support this workaround.