Ok, we all seem to be right about this.
I was able to reproduce this issue within a live environment:
- Switch to Breeze (Dark) Theme(up until now everything works as intended)
- Switch display scale above 100%
- Icons are not monochrome anymore(after relaunching Dolphin etc)
Works on both X11 and Wayland, however setting the scale to a value below 100% (on Wayland that is possible) doesn’t trigger the unintended behavior.
Maybe some of you could confirm that this issue exists for them as well, if not at least in a live environment.
If someone can confirm this issue I could open a separate thread in case @cscs’s mention is not sufficient.