you can literally just check out their profile while playing, why tho, it's not that hard to do that so, ALSO, that would be annoying for the eyes sometimes.
If you mean in discord, then it's already there. If you mean in site chat, eventually I guess the username are already had cyan color, red color or something else. If you mean in game chat, just holding tab, press the "i" button and you will know if that one is a real staff.