(In reply to Alex Deucher from comment #4)
> Does forcing the clocks to high or low fix the issue? (as root):
> echo high > /sys/class/drm/card0/device/power_dpm_force_performance_level
> or
> echo low > /sys/class/drm/card0/device/power_dpm_force_performance_level

I did this test and I can confirm that if I set
power_dpm_force_performance_level to high or log the flickering stops.
So at 144Hz with power_dpm_force_performance_level set to auto there is
flickering.
With power_dpm_force_performance_level set to high or low this bug is not
present.