And since 20200706 it’s possible to choose libCEC version for testing.
Default is libCEC 4.0.4.
By touch /storage/.config/libcec-4.0.5.conf after a reboot libCEC 4.0.5 will be used.
When removing the touched file again 4.0.4 will be used.
EDIT: since 20200715 there will be libCEC 4.0.7 available to by touch /storage/.config/libcec-4.0.7.conf