The Deviantart app is broken, apparently. First, it kept logging me out every time I closed the app (which it didn't do before), now it just won't let me log in, even after reinstalling the app and restarting my phone.

@Chameloshi: Yet somehow, I could still login to DA on the phone browser without problem. It's too slow to use properly, though.

If this doesn't get fixed, I'll have to use my laptop, which isn't something I could do every day.