Toslink output volume

[CentralCoast]

Perhaps you can help me with a mystery. I have my home theater processor connected to my Samsung tv via an Optical link. When using the Netflix app on the tv the processor volume needs to be set to 70. When using the Plex app on the tv the processor volume of 70 is way too loud.
Why would different apps have different volumes via the same Toslink output?

 

[pozz]

This is just a guess, but probably loudness normalization. One platform may have a different target than another.