Upgraded OSMC to Kodi V19.3 TV Screen Black

That is the same error as here reported on the Pi4

Would be interesting to see if adding one of these options to config-user.txt makes a difference
dtparam=audio=on
dtoverlay=pisound

Also the output of edid-decode /sys/class/drm/card?-HDMI-A-1/edid edid-decode /sys/class/drm/card?-HDMI-A-1/edid could be of interest.