I've found a couple of now closed posts regarding font smoothing not working in Wine under Zorin OS. I found a solution to this and felt I should register just to share it, so others who do a Google might find it. Skip to the end for the TLDR version.
I had the same issue in Zorin but I also found it was affecting me in Debian too. But only on GNOME, KDE was fine. It took me hours of googling and messing about with config files, but the former eventually brought me to this command...
xrdb -query | grep -vE 'Xft\.(anti|hint|rgba)' | xrdb
That works, but only for the current session. A logoff or reboot brings you back where you started. I decided to break it down and just run xrdb -query, which gave me the following:
Comparing this to a working system shows that Xft.rgba is the culprit, the command above resets it to rgb.
The permanent solution is to install gnome-tweaks, then open it and go to the Font section. Change the antialiasing from "Standard (greyscale)" to "Subpixel (for LCD screens)". This permanently sets Xft.rgba to rgb and font smoothing now works correctly in Wine.