When you are spectating (or watching a demo of) a match, if the player you are spectating pings another player and switches to free camera, the hero that was pinged remains on the screen and does not disappear unless the player switches back to spectating a player.
This bug is similar to this one: https://project8.dev/threads/add-to-roster-and-make-preferred-hints-stick-around-after-tutorial.4446/
When the match statistics appear, the UI shows "Add to Roster" and "Make Preferred" hints.