I have a 16" M1 MBP. Never had this issue. Connected to a OWC TB4 dock with 2 monitors. I have to use Amphetamine to keep it from going to sleep. Undocking/doc

I have a 16" M1 MBP. Never had this issue. Connected to a OWC TB4 dock with 2 monitors. I have to use Amphetamine to keep it from going to sleep. Undocking/docking works fine. Perhaps you have some process running that is preventing sleep.