On the start screen, there are three options, start with Xfce, Zorin Desktop and Zorin Desktop on Wyland.
With Xfce, the screen resolution is lower than 1920 x 1080
With Zorin Desktop, the screen resolution is lower than 1920 x 1080
With Zorin Desktop on Wyland, the screen resolution is correct, it works with 1920 x 1080.
The start screen does not give the correct resolution, it looks low and the user photo and password are very large.
Well, the Thing is: Here on Zorin 17 it would be better to use Xorg with Nvidia Cards because the Wayland Implementation isn't so far like on a more up-to-date Desktop. So, Nvidia and Xorg should work betetr together - especially the Nvidia Drivers. But when You say that Your System with Wayland works, all is good.