I have similar problems with a lenovo m625q with Stoney graphics:
VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Stoney [Radeon R2/R3/R4/R5 Graphics] (rev d4)
Since 5.15.0-86 (Ubuntu 20.04 HWE):
After entering the password in the dm and mate startup, the machine crashes.
A twin system without graphic login works with out issues.
I have similar problems with a lenovo m625q with Stoney graphics:
VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Stoney [Radeon R2/R3/R4/R5 Graphics] (rev d4)
Since 5.15.0-86 (Ubuntu 20.04 HWE):
After entering the password in the dm and mate startup, the machine crashes.
A twin system without graphic login works with out issues.