When first connecting to Overcast, you must grant consent for the app to interact with Azure on your behalf. This operation is only performed once since the consent is remembered by Azure AD.
If you wish to revoke this consent, follow these easy steps:
Step 1: Go to https://portal.office.com/account/#apps
Step 2: Click on the "Revoke" button that is found in the Overcast card
Step 3: Click "Ok" in the confirmation popup.