Hello.
There should be a transparent colour for chat distances, be it shouting or not. For example, a player right next to me is chatting, their text on my screen should be WHITE. Another player is from a distance about 5-10 meters away, the text should be a bit GREYED OUT. Or transparent.
Another player who is chatting but is about 15-20 meters away, their text should be close to GREY, making it a bit difficult to read the text which is obvious as you wouldn't hear them very well in distance. If the player is at least 25 meters, their text would be dark grey, making it even more difficult to read. Any more than 25, we shouldnt receive the text at all.
The same should go with shouts but with extended distances, so unlike the normal chat where 25 would be greyed out, it should be greyed out at 40 meters in shouting chat. In brief words: The longer distance, the greyed out the text should be.