I was having the same issues as everyone and tried the NVRAM with no luck. I did follow your instructions on Use safe mode to isolate issues with your Mac - Apple Support, and put my Mac Pro 15 to sleep in safe mode a few times and restarted. It is working great and the new Catalina appears to be faster, charges the battery faster and is much brighter on the screens.
I am having an issue with Displaylink working to drive my 3 24" monitors which I will look for any relevant posts.