i'm pretty new to the linux landscape and i'm currently facing the issue that my screen sometimes flickers and glitches out. also some apps don't load completely and stay in a glitchy state.
Did You tried to switch between Xorg and Wayland? If not go to the Login Screen and click on your Profile so that the Password Field appears. It must appeared! When it is appeared You should see in the bottom right Corner a Gear Icon. click on it an You should see 2 Option:
Zorin Desktop (that is the Wayland Option)
Zorin Desktop on Xorg
Wich Option is active You can see on the Dot Marker. Switch from on to the other and then log in and test if it works.
Another Things: Check how are Your Refresh Rate is set up and if Fractional Scaling in the Display Settings is active.