That looks like someone put the non-transparent background logo for a moment. However, it look like that for me. Maybe clear your browser's cache and refresh the page?
New Site Update to the latest version of Xenforo with some changes coming soon - should be around the end of the month. This will be the TH.net 2.0 Version.
I do know this - xenforo dropped the ball by not keeping the vbulletin reputation comments as a feature. The loss of the Reputation comments data when we switched to Xenforo really was the death knell for the site when it came to all the users that left. I know I missed it so much and I got way less interested in the site when that feature was gone and I run the site.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory