So... new update has improved things! There's a 2k resolution now, which is nice. But there's also a 640x360 resolution, which is the new resolution the game resets to on launch and randomly sometimes at the end of a run.
It does so in a window, so it won't break other things like I was seeing before, but I'd still say it's less than ideal for the game to be changing its resolution like that. Also, that small a window on a 15" laptop monitor is kind of hilariously tiny xD