Thanks to your comment I figured out that the issue seems to be with the colored shell themes, the only one that shows everything properly is when I select "Default" on shell theme, all the others have the issues mentioned at the start, so maybe I somehow ended up with the wrong themes?
Even when You have choose for Shell ZorinGrey-Dark? Because the ''Dark'' is the Point. That makes the Background dark. When You would choose ZorinGrey-Light it is white. With Third-Party Shell Themes it depends how it is make.
I use for Example A Theme called Graphite. There it is so, that I have a dark Background on Graphite-Light, Graphite and Graphite-Dark.