GDPR, as a side effect, entitles users to get a copy or their data after a ban, as long as the service has not already deleted the data.
The data subject shall have the right to receive the personal data concerning him or her, which he or she has provided to a controller, in a structured, commonly used and machine-readable format and have the right to transmit those data to another controller without hindrance from the controller to which the personal data have been provided
Would you be able to trust GDPR to actually return “useful” data?