Several users here on reddit confirm the whole thing happens in their cars as well, though right now, it’s not yet clear what’s causing this behavior, given that Apple Music worked just fine literally only a few hours ago.
Most likely, it’s an Apple Music problem causing the app to crash, with Apple expected to release a server-side fix that would bring things back to normal rather sooner than later.
Oddly enough, the whole thing seems to be happening exclusively on devices running iOS 14.5.1, which right now is the most recent version of Apple’s iPhone operating system. And while this could make some believe the culprit is this software update, it is unlikely to be the case because, as I said, Apple Music was running properly on the same iOS version earlier today.
Apple has so far remained tight-lipped on what exactly happens with Apple Music and when a fix is projected to roll out, but right now, it looks to be rather widespread. I’ve tried launching Apple Music on CarPlay with both an iPhone 11 Pro and an iPhone 12 Pro, and the app crashes on launch with both devices.
There’s little you could try right now to bring things back to normal, so your only option is to wait until Apple releases the fix because this really shouldn’t take too long.