Good question. I was speaking from memory, and all I can find when googling is this: https://docs.getutm.app/settings-apple/virtualization/#ballo...

EDIT: I recall vaguely something about it being a problem with Linux guest VMs because it aggressively uses RAM as a file system cache. So it'll just fill up RAM to the max when reading from disk, and overwrite this if it's later needed by applications.