I have been seeing this as well. For me it seems to be power-profiles-daemon enabling amdgpu_panel_power when the battery hits 30%. I have disabled it with this and have not seen it again.
# It seems there is a bug when amdgpu.abmlevel that kills the backlight now
systemd.services.power-profiles-daemon.serviceConfig.ExecStart = [
""
"${pkgs.power-profiles-daemon}/libexec/power-profiles-daemon --block-action=amdgpu_panel_power"
];