Had a similar issue.
In my case it was after an update & upgrade.
It seems the fake kms driver is depreciated, so raspOS has changed it into the kms driver.
In my config.txt I had to change the line
dtoverlay=vc4-kms-v3d into dtoverlay=vc4-fkms-v3d
My Pi won't work with kms , only with the fake kms.
Unfortunately, after each upgrade it is changed back to kms, so it requires manual intervention after upgrading.
