Non-functioning drivers after BIOS update

It looks like that the BIOS update on the HP 250 G7 removes the Machine Owner Key (MOK), so it has to be added again, as described here: https://wiki.debian.org/SecureBoot. Otherwise the custom drivers (like the 8821ce) will not be loaded, if SecureBoot is on.

Fixing it is actually only one step:
# mokutil --import MOK.der