Complete different issue.....
First what was reported here is missing virtualbox-guest-modules.
Issue with the host not running found, nothing to do with the modules, but caused by the libvpx update, virtualbox-qt needs a rebuild for that ( you can test by installing libvpx 1.10.0 from your cache, don't leave it installed, because all others that needed a rebuild like qtwebengine, need libvpx 1.11.0).
ldd /usr/lib/virtualbox/components/VBoxC.so | grep "not found"
libvpx.so.6 => not found