Only the latest release receives fixes. Older versions are superseded by each new release, which installs directly over any previous version with the same signing key.
Please do not open a public issue for security problems.
Report privately by email: jarsi@jarsi.org. Include the app version (shown at the bottom of the settings page), your Android version, and steps to reproduce. You should get a reply within a few days.
BetaScout signs in with your own Google account, stores the session cookies encrypted on the device only, and never sends them anywhere. Anything that could leak the session, the app list, or membership data off the device is in scope and taken seriously.