the color of the name displayed in the player list (tab) is sligthly off-color, for exemple "gold" apear more brown than gold
steps to reproduce :
create a new team, then change it's color and add yourself to the team, and press tab (this work only on multiplayer, as you can't see the player list on singleplayer), you'll see a different, darker color than if you typed something in the chat
(note : I can't really tell if it's darker or semi-transparent)
Affects 20w18a also. It's not a colour thing, all player names appear more translucent.
Reproduction steps for singleplayer:
1. Create a new world
2. Run
/scoreboard objectives add test dummy3. Run
/scoreboard objectives setdisplay list test4. Give yourself a score:
/scoreboard players set @p test 55. Show the player list