In the layer panel, the app shows the "Transparent Color" as a Dark gray. This fits well with the "Dark interface", but when we use the "Light theme" I believe the color representing the transparent color can be also a Light gray, not a Dark gray, to fit the theme. Same for the layer with a big "X", the background can be a Light gray too if we are using the "Light theme"
Besides anything else, is a little hard to read thumbnails with a dark background when we are doing outlines and only have black lines in the layer
Check the images I posted above in this thread with a draw of a smile. @alfanders photoshopped a simulation of what I mean, he makes the background of the layer a Light gray