This is somewhat normal and expected behaviour. As soon as elements don’t fit on the line, they will wrap. It happens faster on the New tab for example, because that has more elements.
Possible it happens faster now because of spacing tweaks, but this is considered normal behaviour.
Would it be possible to keep the new topic button on the right, even if it’s on a different line than the nav links? Especially when I switch between English and German a lot, a new topic button that is constantly displayed on the right-hand side would be helpful.
I believe this is what most needs to be addressed. Larger text would suggest a bigger target for links and less of a need for more padding between elements in order to maintain the nav bar.
Or do what Moin has proposed and maintain the general layout of the nav bar if not the exact structure.
This solution preserves muscle memory, and there is also a user preference for a default topics listing so changing them on the fly is probably less common once set.
For me, it’s not about fewer items. The problem starts with the fact that “ungelesen” is longer than “unread,” and “angesagt” is longer than “top.” So, admins would have to remove links for everyone because it doesn’t look that beautiful in German.