ROBLOX, within the past year, added a feature where if you send someone a friend request in-game, it also sends a friend request to them on the site. This can be useful if you don’t have the chance to accept someone’s friend request while you’re in a tense battle and forget to accept it afterwards. If you accept their friend request, it’s accepted on the site, but if you decline their friend request, the request isn’t cancelled on the site. If you explicitly decline friend requests in-game, they should be declined on the site as well.
In client bugs because this sounds more like a client team thing (having the client make a web request to decline the friend request)