Looks like KDE Plasma 6 and QT6base got updated, but KDE hated the version of QT6 it upgraded to. Login did the loading screen, then loaded my session apps, then crashed to a black screen where only alt-f2 worked...sometimes.
Journalctl showed everything saying libQt6Core.so.6 was n/a in stack trace after stack trace. Via serial console I could verify it was there, upgraded, but even konsole through stacks over it.
While it shouldn't matter what my arm64 / aarch64 platform is, a bug report is never complete without it:
M1 Mac -> UTM (QEMU for mac) v.4.5.2 in Hypervisor mode (no cpu emulation) (Comes with UEFI booting) - Works as a daily driver. Was able to rollback via the hypervisor.
The upgrade that broke me was going from qt6-base 6.7.1-3 to qt6-base 6.7.1-4.