Mangrove Reviews Signer
Your MapComplete key
MapComplete signs your reviews with a key that it keeps in your OpenStreetMap preferences. The Mangrove signer can link that key to your reviewer identity, so the reviews you wrote in MapComplete count under your identity.
Every app you have allowed to read your OpenStreetMap preferences can copy that key. With it, such an app could write, edit and delete reviews in your name. Removing the key from your preferences puts it out of their reach.
Both buttons log you in to the Mangrove signer with your OpenStreetMap account. The signer then shows the reviews of the key, and acts once you confirm.
OpenStreetMap asks you to let Mangrove Reviews read your preferences, and to change them when you remove the key.