LE10+ uses a completly different (ground up rewrite) display pipeline to LE9.2, so yes there is a HUGE software difference. The main way this manifests for users is that almost all config.txt tweaks for forcing video and audio output used in the older display pipeline are no longer supported using config.txt, and are now achieved using standard Linux DRM methods/properties.
It would be helpful if you described how everything is physically cabled/connected, and please share the "pastekodi" URL taken from the LE9.2 and a clean-install LE12.2 (or LE13 nightly) image so we can see kodi/kernel and various bits of config from the systems; the kodi.log on its own isn't giving us the full picture. If the RPi4 is connected to the projector using the HDMI socket nearest the power connector, please also run edid-decode /sys/devices/platform/axi/axi:gpu/drm/card1/card1-HDMI-A-1/edid | paste and share that URL too.