Details about used graphics and display hardware are missing. Is upgrading to Ubuntu 22.04 an option? What graphics hardware is used?
Update: I thought about this general problem quite a bit lately, it is not as trivial as one would think, also of general interest, as the problem has come up more than once. After quite a bit of tinkering, I came up with a few new additional improvements. If you are still interested in a solution, I will provide advice for free - well sponsored by Mathworks, using the 2nd of three Mathworks sponsored support incidents for non-trivial issues faced by users, Neuroscience - MATLAB and Simulink Solutions - MATLAB & Simulink .
-mario