Nextcloud Android is the Android client for Nextcloud, a self-hosted productivity platform. Prior to version 3.19.0, sensitive tokens, images, and user related details exist after deletion of a user account. This could result in misuse of the former account holder's information. Nextcloud Android version 3.19.0 contains a patch for this issue. There are no known workarounds available.
https://hackerone.com/reports/1222873
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xcj9-3jch-qr2r