I have the exact same issue on my 16". So much so that I've started preferring using my much smaller iPad as the second screen using the sidecar feature instead

I have the exact same issue on my 16". So much so that I've started preferring using my much smaller iPad as the second screen using the sidecar feature instead of my main 4k monitor. Although I love everything else about the MBP 16, this issue drives me crazy.