Rejoining a room causes an error

I have some code that has been running for the last 3 years, that recently stopped working correctly.

Players can join rooms by calling   PhotonNetwork.JoinRoom(RoomName);

When a player exits the room by calling  PhotonNetwork.LeaveRoom(); The OnLeftRoom Callback is called that  PhotonNetwork.Disconnect(); and sends them back to the main menu.

When this player decides to hop back into the same room they just left the following error comes up : Found inactive UserID '156.....9a9a', but not rejoining (JoinMode=0)

This is new behavior as in the past the player could jump back into the room ( as a "fresh" player). I have not updated Photon SDK locally in the last 3 years, could this be the issue ?