I’m not sure what happened, but I think this is the issue:
[ 10.735820] SELinux: Context system_u:object_r:qubes_qubesdb_daemon_exec_t:s0 is not valid (left unmapped).
[...]
[.[0;1;31mFAILED.[0m] Failed to start .[0;1;39mqubes-db.service.[0m - Qubes DB agent.
It’s probably a SELinux labeling issue that caused the qubesdb systemd service to fail, which made everything unusable because this is a critical component.
If you still have the template, try disabling SELinux and see if that allows it to boot:
#dom0
qvm-features fedora-41-xfce-EXTRAS selinux 0