"Failed to Sign In" screen popping up multiple times in the last day or so

To be clear, the sign in process itself works fine (I use Sign in with Google). What I'm experiencing is when I've already been playing, leave the app, and upon re-opening it'll crash and send me to the Failed to Sign In screen. It only seems to happen upon opening the app, not during gameplay.

I'm not sure if it's something occurring since the last update or if this is a known issue, but I can't find any other similar posts with a quick search.

(And while we're at it I'd like to take this opportunity to gripe about AR Buddy getting turned on every time I re-sign in.)