It's running the infotainment display(the one in the centre of the car) , but not the driver display. Fortunately I've never heard about the driver display crashing while driving, so at least Volvo had the good sense of making sure that is solid - but the infotainment display is known to crash frequently requiring a hard restart(you hold the button under the display for at least 10 seconds then the entire thing reboots), which maybe it's critical but means you can't change any of the climate controls(other than windows demist since it has its own button, thankfully) while the screen reboots.

Correct, the car can function without the infotainment system but you lose conveniences like climate control, the backup camera, and sometimes even audio, which is weird because you get no feedback from the turn signals. It’s not great but not an immediately pulling over kinda thing.

All systems in a car are safety critical. If your infotainment system is freaking out it is taking your eyes off the road.

The same way that updates to Google Maps and Apple Maps kill people due to UI changes.

All systems are safety critical.