Never saw this before. I was in the field trying to unlock a NFZ (application approved) and got this notice. Internet active and working. Rebooted, logged out and in, no change.
P4P V 2.O

Hi UAViator53. If the app prompts a "Disconnected" warning, it can be determined that there is an error with the Flight Controller Serial Number. Please go to the DJI App > General Settings > About >Flight Controller Serial Number and check whether the serial number submitted on the DJI's official website matches the Flight Controller Serial Number of the connected drone. If not, please submit an unlocking request again. We appreciate your patience. Have a great day.