Unigrids has no server of its own and collects no data: the log stays on the device and syncs only through the user's own iCloud. The things worth reporting are therefore in the app itself, for example a way for a backup file, a deep link or a downloaded brochure to read or alter data it should not, or anything that sends user data off the device.
Please report a vulnerability privately through GitHub's private vulnerability reporting rather than in a public issue. Include the steps to reproduce it, the platform and OS version, and what you expected to happen. You will get a reply as soon as I can manage; this is a hobby project, so allow a few days.
Only the latest release is supported.