The Big Sur Sneeze
This has happened to me a few times. As I’m using my 2019 16" MBP, it lets out, at some random moment, a startlingly aggressive “Fehhhhh,” and then it shuts down.
It sounds as if the fan goes to 11 for about a second, and then it turns silent and dark.
To be clear: it’s completely unexpected. This is not happening when I shut down the computer. It happens whenever… it wants? Is bored? Is tired? I dunno.