Account linking happened May 6th. It is on the graph as point “A.”
There is a small increase in the decline of the player count, but you had already lost almost 200,000 players since the last peak on April 1st!
So between April 1st and May 6th the game went from around 370,000 players to around 170,000 players, and the current player count literally can’t drop the same level because that would be less than zero.
So, the bigger drop came way before account linking, friend. The game was already dying, and the account linking just firmly put it out of its misery.