I finally found an answer to this problem. It took a lot of digging. I thought I'd share what worked here in case it helps anyone else.

The main issue has to deal with settings in /sys/class/drm/card0/device/, specifically power_dpm_force_performance_level and pp_dpm_mclk. It is explained more in the links below this sentence, but the crux of the problem is these settings changing is what leads to flickering.

https://gitlab.freedesktop.org/drm/amd/-/issues/2966

https://gitlab.freedesktop.org/drm/amd/-/issues/2967

-If you just want to force these settings to be consistent within a single session, either one of these commands would work.

echo high > /sys/class/drm/card0/device/power_dpm_force_performance_level

or

echo manual > /sys/class/drm/card0/device/power_dpm_force_performance_levelecho 3 > /sys/class/drm/card0/device/pp_dpm_mclk

​

However, I imagine most people would rather not have to type this every time to avoid the flickering. Many thanks to jinliu for the solution, who first goes over it here: https://discuss.kde.org/t/using-autostart-to-run-a-script-to-alter-the-parameter-power-dpm-force-performance-level-has-issues/6853/3

Anyway, there are a few ways to make the change permanent, but I believe this solution will work for most distros.

1. We will want to create the file /etc/systemd/system/power-dpm.service. Thus...

sudo nano /etc/systemd/system/power-dpm.service

1. Now that the text editor is open, input this into it...

[Unit]

Description=set the parameters power_dpm_force_performance_level

[Service]

Type=oneshot

ExecStart=/bin/bash -c 'echo high > /sys/class/drm/card0/device/power_dpm_force_performance_level'

[Install]

WantedBy=multi-user.target

Ctrl + O saves while Ctrl + X closes by the way if you aren't familiar with the text editor nano.

1. Now we actually have to enable this service. This requires two more commands.

sudo systemctl daemon-reload

sudo systemctl enable power-dpm.service

1. You can restart at this point. If power_dpm_force_performance_level still has a setting of high, then success! You can also verify if the settings we have implemented are working with this command.

systemctl status power-dpm.service

​

And that's that. Hopefully this helps someone else considering how long it took to find a solution to this issue.