It happened in https://en.wikipedia.org/w/index.php?title=Gunabati_Union&action=edit&oldid=679732408 , and I can also reproduce this myself:
- Use Firefox.
- Translate [[Mariupol]] from English to Hungarian.
- Find the table.
- Delete text from a cell.
- Write different text.
- Publish.
Result: an unnecessary <br> is added.
My test is at https://hu.wikipedia.org/wiki/Szerkeszt%C5%91:Amire80/test_02 - search for "her be br".
This is probably similar to T97942.