Since it is not possible to change the color or format of PGS subtitles it would be incredible helpful if one could change the brightness of them, being able to dim them. So if the subtitles are white or too bright they look more like gray. Bright subtitles look very bad and distracting in dark scenes.
There is also another problem with subs, in general.
When watching SDR content with normal levels of brightness, gray subtitles, for example, look dim as they should, however using the same subtitle setting in HDR returns way brighter subtitles. There should be a way to change the opacity of both subtitles independently, so both SDR and HDR have different settings.