Ah - ok thank you for confirming! I was looking at the versions on the kiCad downloads page and 5.1.9 was the version just below the 6x versions so mistakenly thought it was latest.
Keep in mind that “not supported” does not mean that it does not work. I’m barely fluent with Kicad, but I have it installed on an Intel MacBook Pro running 10.14.6 and it installed and seems to operate correctly. It also installs and starts up with macOS 12.6 on my newer i9 MacBook Pro. If there’s a bug, it would be most polite to verify that on a supported platform, but then again, it’s also likely that “a bug is a bug” and other than installation, there’s little reason to expect the two platforms to be functionally different. Again - total noobie here, but 6.0.7 does install and start up just fine on both 10.14.6 and 12.6