question

I made my own cheap solution for this, it's only downside is you have to manually logout these users who lost their devices, that shouldn't be problem if you have support system you can also check events to see if they are faking, you can wait couple days.

      private void OnGetUserDataSuccess(GetUserDataResult result)

      {

          string deviceId = SystemInfo.deviceName + "_" + SystemInfo.deviceModel + "_" + SystemInfo.deviceUniqueIdentifier;

          if (result.Data != null && result.Data.TryGetValue("DeviceID", out PlayFab.ClientModels.UserDataRecord userDataRecord))

          {

              string existingDeviceId = userDataRecord.Value;

              // If "SystemInfo.deviceUniqueIdentifier" is already stored and it's the same as the current value, do nothing

              if (existingDeviceId == deviceId)

              {

                  Debug.Log("Go For Second Confirmation");

                  Invoke("GetSecondUserDataDelayed", 5f);

                  return;

              }

              // If Logout Before

              else if (existingDeviceId == "LOGOUT")

              {

                  Debug.Log("Updating Device ID of Log-Out User");

              }

              // If "SystemInfo.deviceUniqueIdentifier" is already stored but it's different from the current value, update it

              else

              {

                  Debug.Log("Device ID has changed. Block User - " + existingDeviceId);

                  multipleloginScreen.SetActive(true);

                  return;

              }

          }

          // If "SystemInfo.deviceUniqueIdentifier" is not stored in user data, add it

          else

          {

              Debug.Log("Device ID is not stored in user data. Adding it.");

          }

          UpdateUserDataRequest request = new UpdateUserDataRequest()

          {

              Data = new Dictionary()

              {

                  { "DeviceID", deviceId }

              }

          };

          //Go For Second Confirmation Afterwards

          PlayFabClientAPI.UpdateUserData(request, OnUpdateUserDataSuccess, OnUpdateUserDataFailure);

      }

You call it with this after login

PlayFabClientAPI.GetUserData(new GetUserDataRequest(), OnGetUserDataSuccess, OnGetUserDataFailure);

Players can still log-in if two player click to log-in button in same time, to solve that you have to add another GetUserData with interval of 5 seconds, so when two players call UpdateUserData only one of them will stay and after 5 seconds you will get GetUserData and only one of them will pass the log-in screen.