This would indicate that the fix according to Debian Bullseye Bug causing Klipper to no longer find the printer board was correctly done.
If it had not worked you would not get a result.
Can you explain, what you are trying to achieve?
Is the M8P your main MCU and connected via USB to your host? If yes, then you need to compile Katapult with the respective USB options and not as CAN.
Flashing it as USB connected main MCU would work like shown here: CanBoot: Flash BTT SKR 1.3 / 1.4 / 1.4 Turbo
Edit:
dmesg is a tricky thing: It contains a lot of low level information and something that is marked as an “error” often is gracefully handled but shown anyway. Rule of thumb for dmesg is: If it is working, then happily ignore the errors unless you want to become a Kernel or driver developer