Thought at first it might be a firmware thing. It was low on battery, so I thought it may have died but the screen wasn't told to turn on again....? But it is acting like it's on the watchface, ie quiet time still can be toggled, notifications still buzz, backlight still turns on when a button is pressed. I don't know the menus by heart enough to test anything else.
Bug report reply says the screen might be shot, but to ask around here 😢