From the information gathered from your links, this is somethings the devs know about. It’s a Xen bug that was fixed in version 1.14.1 that affects the latest Intel “Lake” processors. This patch won’t be included in Qubes OS 4.1 because it also causes some other issues in some other computers which means it’s not stable. So basically the only immediate option is to build Qubes OS on your own and update the Xen version.
Do you have any links about how to build Qubes on a linux OS such as Ubuntu?
Anyway, thank you very much for the links, means a lot to me.