In the background
QEMULauncherUTM virtual machine
◐ Close the app instead
A virtual machine running in UTM.
What it is
UTM uses QEMU or Apple’s virtualisation to run other systems.
If you close it
The virtual machine stops as if its power was cut. Shut it down from inside first.
The verdict
◐ Close the app instead. A part of an app. Closing it alone breaks something, so close its app.
In Activity Monitor
QEMULauncher
From Procession’s guide, in the words the app shows.