> I have other issues related to external screens, with 10.14 and 2018 MBP: I usually run the laptop with closed lid and an external screen at work and at home; and use it in “laptop mode” during my commute. Now, sometimes (once a week?) when I plug it into the external screen, it just won’t wake up, unless I open the lid, and then it still won’t recognize the external screen. Have not yet found out a reliable way to resolve this, but I usually manage with turning the monitor off and on again and/or unplugging/replugging it, possibly a couple times each.

I've previously had these problems, and they were made dramatically worse on Catalina. Each monitor has about 50% chance of correctly loading in, on what used to be 90%. My USB mouse (which is plugged in to the displayport monitor) also loads the incorrect drivers until I unplug and replug it.