Hrm. I had similar problems with my M1 Macbook Air with this monitor, and I ended up having to set the monitor to continue charging USB devices while off. Otherwise the monitor would stop charging the laptop, MacOS would wake up, and wake up the monitor.
Apparently I’m not alone in not being able to change the power profile in Linux, Lenovo broke it with a UEFI update for some Windows functionality. A fixed firmware will ship eventually, the author has a beta and confirmed it’s fixed.