Entire host macOS was crashed. Must be a bug with macOS. May be it is fixed by now, I don't really want to try as I don't like when my OS crashes. You can inspect qemu command line from UTM, I'm not sure if I saved my scripts, but there're some weird flags which I had no idea what they're for, but when I removed them, it was boom, reboot.

Were you trying to use more than 8GB of memory? There's an option to pass to qemu for highmem. Could be hitting this issue: https://github.com/lima-vm/lima/issues/713

I think that I hit something similar to this issue: https://github.com/utmapp/UTM/issues/3946

I didn't set too much RAM, definitely less than 8GB.