If someone sends you a friend request in a game, you get two notifications. One from the player list, and one via an on-screen popup.
If you accept the one in the player list, then decline the one from the popup, the person you just added is then removed.
I understand why this happens, so a potential fix is to remove the popup (if it exists) when a player accepts or declines via the leaderboard.
There, posted it Buddy. 
That’s pretty good to be honest, you can then easily change your mind if you found out that guy didn’t turn out like you thought he would be. 
You have like, 3 seconds to change your mind in that scenario. Plus, it’s not like you can’t remove them via the player list.
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