[Question] Any ideas on what could cause 'random' screen wakeups after upgrading to Catalina?

I did a clean install of Catalina a few weeks back, but unfortunately my machine now wakes from sleep (with some regularity, 2hrs usually) and turns on the monitor. Before 10.15.1, it would actually go to the lock screen, but now it just wakes the screen and goes back to sleep immediately. I have researched extensively and tried everything I could find to debug or fix the issue, but instead of explaining all that, it would probably be more useful to get advice about the problem from the community. I'll post machine details below, but I suspect it may be update related or a generic OS preference issue (e.g. disabling wake for network access, which is one thing I did that had no effect ). Any hints about what to look for in terminal (e.g. with log show --style syslog | fgrep "Wake reason") or any other clues would be most appreciated!

Motherboard: Z390 designare; CPU i9-9900k; GPU: Sapphire pulse RX580; vanilla install using clover; NVMe boot drive; LG 5k2k monitor over DisplayPort.