They describe a leaderboard built from server members' shared gaming activity, while actual rollout remains unconfirmed.
When It Appears
“{name} (You)” can appear on a server view that ranks shared gaming activity and shows a timed competition when Discord displays the marker that identifies the current user with You beside their name.
What It Means
When “{name} (You)” is shown, the current step is presenting the marker that identifies the current user with You beside their name.
A user who saw “{name} (You)” in Discord is likely searching to confirm that it means the marker that identifies the current user with You beside their name, where it appears, and which state it describes.