I installed mainline kernel 5.6.14-050614-generic from the Ubuntu Mainline Kernel repository and now it works perfectly, I haven't encountered any black screen on boot on two days.
Whatever it was it seems to be fixed in 5.6 kernel series (no idea about 5.5), but I don't know what was fixed exactly, I heard 5.6 fixed some CPU freezes and overheating issues with Asus TUF Gaming Ryzen laptops.
I installed mainline kernel 5.6.14- 050614- generic from the Ubuntu Mainline Kernel repository and now it works perfectly, I haven't encountered any black screen on boot on two days.
Whatever it was it seems to be fixed in 5.6 kernel series (no idea about 5.5), but I don't know what was fixed exactly, I heard 5.6 fixed some CPU freezes and overheating issues with Asus TUF Gaming Ryzen laptops.