Per Renee RM8 does not support dark mode and if you click on a citation note you get a black popup window. In light mode that window displays the note contents. Perhaps this should be added to the appropriate place in the wiki.
Mac dark mode is very helpful to increase contrast and reduce eye strain compared to the relative glare of light mode. I wrote a very simple automator app to switch and you could also write a shortcut to do the same thing. Spotlight pulls up the app (Light-Dark) and it toggles dark/light.