Graphical glitches on startup (Ubuntu 21.04)

Hello everyone,
On my Chuwi Gemibook I find a consistent presence of graphical glitches (as if the frequency were wrong) when starting Ubuntu and the only way to eliminate them is to change the resolution and then return to the default one.
Unfortunately, I only detect this problem on Ubuntu while with other distributions I never had problems.
How can I try to solve?