I also have this issue on a thinkpad L14 with ubuntu Ubuntu 20.04.3 LTS, AMD Ryzen 7 pro.
The issue appears with the kernel linux-image-5.13.0-1022-oem when is waked up from sleep.
The issue is not present with older kernel version. Downgrading to an older version solves the problem.
The laptop becomes useless without an external display.
I also have this issue on a thinkpad L14 with ubuntu Ubuntu 20.04.3 LTS, AMD Ryzen 7 pro. 5.13.0- 1022-oem when is waked up from sleep.
The issue appears with the kernel linux-image-
The issue is not present with older kernel version. Downgrading to an older version solves the problem.
The laptop becomes useless without an external display.