This feature is currently disabled.
What is a Spectator ID?
Spectator IDs are the numbers visible below player's cards (bottom right on the image) on the death screen recap and when spectating a player. You can enter that ID on this page to find the player's profile page. Spectator IDs are also displayed next to profile views on players profile pages.
What about anonymous mode?
You can already see anonymous mode players names while spectating. If this changes in the future, this page will be removed.