This is really bad. I was expected, the KVM maintainer, you, to check out testers-only (binary or source) releases for KVM compatibility for both in-place upgrades as well as new builds.
In Non-Qubes-Whonix 13.0.0.1.0 X issues I explicitly asked you for KVM testing for 13.0.0.1.0 because I do not regard KVM compatibility naturally working.
Now we are in a bad state. The downloadable KVM version has a grave usability bug right after download and import that cannot be hidden by an update. (It could be fixed by a stable upgrade that eats up time but would get visible once nonetheless.) Fixing the mess out of the box would require a new build, which is a time consuming process from build, test to release.
Any fix, simple or not should be tested. Looking at the commit https://github.com/Whonix/whonixcheck/commit/88ce7981e57b564aef421aebdbd3e7174c7517c8 again it looks pretty obviously wrong.