Due to this, selecting an unsuitable color in "color settings" lets icons (almost) disappear.

In settings, color themes must differ enough to let e.g. icons not disappear or to make them almost unreadable.

Example is:

In Settings -> Color -> Set to dark grey  (10 o'clock, if you see the circle as an analog clock), change to Climate, select any heat icon -> Icon is selected and almost disappears/unreadable