I tried the LE 12 image you sent. First I ran it without the ssh parameter. It got stuck in the same loop I initially described, except this time, it skipped stopped kodi.service, so it was just
starting kodi.service
started kodi.service
starting kodi.service
After adding the ssh parameter, it does the same thing. It doesn't constantly start and stop sshd.service like it did in LE 11. It even showed the kodi 21.0 splash screen for a second or 2, before returning to the LibreELEC boot screen looping between starting and started kodi.service again. Still can't connect via ssh using the command I mentioned earlier.