Diff highlighting fails on tags with diacritics in suggested edits reviews

Question

This may seem like a ghost edit: https://es.stackoverflow.com/review/suggested-edits/51233 (SOes).

It turns out the tag matemáticas was added as a suggested edit, but it was rendered as:

when it should have been:

The DOM inspector shows:

<a href="/questions/tagged/matem%c3%a1ticas" class="post-tag" title="" rel="tag">matemáticas</a>

missing the <span class="diff-add"> it should have had:

<a href="/questions/tagged/matem%c3%a1ticas" class="post-tag" title="" rel="tag"><span class="diff-add">matemáticas</span></a>
<!--                                                                             ^^^^^^^^^^^^^^^^^^^^^^^           ^^^^^^^ -->

---

I found out this is happening on all tags with diacritics: ^{(*this is enabled on a per-site basis)}

1. Diff working in the body, failing with tags:
   https://es.stackoverflow.com/review/suggested-edits/18543 (SOes)

2. Two tags added, only the "ASCII" tag is highlighted:
   https://es.stackoverflow.com/review/suggested-edits/20105 (SOes)

3. Diff works as expected on /revisions (no-repro here):
   https://es.stackoverflow.com/posts/197/revisions (SOes)

4. Reproduced on different sites:

   • https://spanish.stackexchange.com/review/suggested-edits/12155 (Spanish)
     (bug report by @fedorqui)
   • https://pt.stackoverflow.com/review/suggested-edits/116711 (SOpt)

5. This doesn't seem to be an issue with Russian characters:
   https://ru.stackoverflow.com/review/suggested-edits/174038 (RU.SO)

Answer 1

This seems to have been fixed somewhere in the past:

See how "matemáticas" is highlighted, while it was not in the image of the question. That is, the element has now a <span class="diff-add"> which did not have before.

I checked the rest of the links given in the question. All of them are working well.