On mobile, the Debate and Discourse forum appears to have a large grey version of the "jailed" avatar overlay on top of it. I can enter the forum itself, but this appears over where the threads are listed. When I try to open a thread underneath this overlay, it invariably takes me to user Harry Dresden's profile
A few days ago it was also happening in the SE++ tv thread, but that stopped after a few page refreshes
Posts
Possibly related, but much less common - a page will stop displaying posts, and instead have the toolbar permanently on display past a certain stretch of the page.