With boot.initrd.systemd.enable = true;, my screen's brightness is reset to 100% on reboot. systemd-backlight@leds:tpacpi::kbd_backlight.service starts up but systemd-backlight@backlight:amdgpu_bl0.service doesn't. Not sure how to debug this. I'm on a thinkpad T14s.

Clarification: the issue is not that the brightness level is 100% in the initrd, but that it stays 100% after booting. In other words systemd-backlight never starts.