Setting MINIMUM refresh rate to save battery and most importantly STOP screen gamma/color changes at low brightness

I have a OnePlus 8 Pro that uses PWM. Refresh rates switch between 60 and 120 Hz. When it does this the gamma changes (or maybe color) and creates a flicker effect at low brightness levels that makes videos unwatchable.

I’ve tried using adb to set user_ and peak_refresh_rate to 60 but this does not change anything. The only options in settings is to set the screen to 120Hz which I do not want to do because of unnecessary battery drain.

Is anyone able to help with this? Is there a different setting for /e/os than other ROMs?