Note how the 'CATEGORIES' title overlaps the upper banner, FORUM link, instead of being it's own header? Shouldn't it be above 'Topics', but below the banner?
Curious. Upgrades, sidegrades, nogrades.
It disappears if you scroll a little down, comes back when you scroll up.
And as @xfpd mentions, no avatar in the right top. Further the post count on the avatar does not disappear after opening a topic from the list of "subscribed" topics.
For those for who it is annoying, the below will prevent the forum logo problem, not other problems. Layout will change slightly but functionality is there.
I logged out and logged in and the forum is back in good form. I suspect old tools were hanging around in cache, and a logout/login refreshed them. The new forum asks for two-step login, so the issues we have seen is probably from those new tools being loaded.