Device attach fails on debian 11 based AppVM

I did an in-place upgrade from debian 10 to debian 11 for all my debian templates. AppVMs based on the debian template with the most installed packages at all have a persistent problem now. When I try to attach an USB device, I get the following error:

“QubesException - Device attach failed:”

That is strange because I never edited the Qubes Policy Rules. Who would know what the problem could be?