There has to be an existing task about this but I can't seem to find it.
In https://en.wikipedia.org/w/index.php?diff=662007607, the following line was added:
* [[Proton beam writing|'''Proton beam writing''']] '''<nowiki/>'''uses a focused beam of high energy…
This issue us similar to T98887 in that it resulted in an empty styled nowiki, but the cause seems to be different (there weren't any pre-existing unbalanced quotes in this case).