Hey,
more often I encounter that text is unreadable because of text wrap, see here:
I cannot reproduce but almost certainly an issue with the templates on this wiki. Should be discussed on the template talk page.
I am unable to replicate this on https://de.m.wikipedia.org/wiki/Spanischer_Bürgerkrieg
@Onny what browser is that?
This is likely a problem with the associated infobox so will likely need a template style fix. Once I can replicate this issue I will make sure I fix it with the appropriate edit!
I can't see any issues in MobileFrontend/Minerva relating to this, so can only conclude there is some problems in templates somewhere.
I dont have a web inspector here, but this looks like a typical case of where an infobox is not using the infobox class, or there being some sort of wrapper around the infobox, that prevents it from talking up full width. Seems like a de.wp problem to me.