As far as I know yu have no options…
First, I would ask if the drone operates normally or is it fling with the 20-meter restriction? If it is operating normally I would leave it alone and enjoy it… However, in the past, some updates to the DJI Fly App has caused the drone to lose its log in credentials and without logging in with the account credentials, you can fly a DJI drone without logging into an account, but your flight is strictly limited to a maximum height of 30 meters (98 feet) and a distance of 50 meters (164 feet). For full capabilities, you need an active account.
I am sorry, but I cannot be of more help…