Hi Piotr, Thank you for your reply. I almost missed it, sorry to say.
> You are using non-bullseye kernel, bullseye is on 5.10.0-9-amd64. Where is that from?
I'm pretty sure you hit the mark! I had completely forgotten that I built my own kernel to try out a new driver. I'll either upgrade to testing or downgrade to the stable kernel.
Thanks again! Matthew