amdgpu broken on bookworm?

[Jeffrey Chimene <jeff@grandadventuresranch.com>]

Something happened to my amd firmware for a ryzen3 3200g. A few weeks 
ago, this machine made an uneventful transition to bookworm. I'd 
originally installed bullseye and the non-free firmware package to get 
the firmware for this setup. Everything was fine until yesterday, after 
some bookworm updates and a reboot. No more video driver for X.

I've tried downgrading to stable from testing. No joy.

I've wiped /lib/firmware and reinstalled firmware-amd-graphics. No joy. 
I've checked

I just booted ubuntu live and graphics are high resolution.

It feels like there's some setting in /proc or /sys that got changed 
accidentally.

Any debugging tips?