The one I set up uses virtualization and definitely still uses qemu.
If you're seeing it use the hypervisor framework, it's possible that's changed since I set mine up and they just haven't seen fit to advertise that change on the web site, which still claims that it's "based on qemu."
(I'm using UTM 3.2.4... just because that's what I used to migrate my data from my old linux laptop to my new mac, and I haven't needed to change it.)
QEMU can do both virtualization (through Hypervisor.framework) and emulation. When you select "Virtualization" in UTM you have a checkbox "Use Apple Virtualization" which makes UTM use Virtualization.framework instead of QEMU. For "Emulation" it always uses QEMU.
