Thanks for 10/23! Unfortunately, as with version 23.04, it doesn’t seem to work on KVM. Every time I try to change something in the settings - like changing the resolution or just checking the energy settings - everything shuts down and takes me to the login screen. I checked this behaviour on Ubuntu Budgie 22.04 on a laptop and on Linux Mint Lmde on a PC, always the same behaviour.
Similar in virtualbox as well.
What i found here was to ensure host graphics were also used i.e. 3D acceleration with 128mb virtual graphics.
You will need to ensure similar configuration with qemu.
Even if I increase virtual graphic memory to 256 stil nothing.
The key is to make sure you are using passthru to your host graphics rather than just the virtual graphics driver
This is also the case for me (ubuntu24.04.2), and I often log out automatically, and the virtual machine memory is allocated 8G.
At the risk of sounding like a turncoat, I’ve often thought that Ubuntu 24.04 introduced problems that 22.04 didn’t have.
Among them, to stay on the subject of VMs,the fact that Gnome boxes stopped working, or worked every other time. As a result, I forgot about VMs.
Out of curiosity, I’ve just tried 46.0, which is available in the repositories. It seems to work again.
Wait and see and finger crossed… 
All - many virtualisation crashes have been identified as this bug https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1861609
Has been occurring for many years. The Xorg project has finally merged Ubuntu’s proposed fix.
As such, Ubuntu - as you can see in the statuses - are now looking to rollout fixes.
If you can, please do help out with the testing via that launchpad issue.