(Gotta blog this out so people don’t question their sanity. Too much chatter on Twitter with no documentation.)
You’re not crazy. Twitter is untiling the background image in a lot of peoples’ profile. And it wasn’t a one-time thing that we can now repair. It happened, you set it back. It happens again.
Guess who’s not crazy.
But it’ll probs break again.
The Twitter support account, which regularly tweets about known bugs, has not mentioned this in the week-ish it’s been going on.
Update: Found this in the Twitter developer forums. Twitter engineering knows about the background tiling issue as of 4 days ago. (But asks for it to be submitted to @support, not developer area. Technically makes sense. But there is no publicly-searchable support forum, so I’m sympathetic to why the user did it.)