Why is Google giving me warning about unverified app?

Google is trying to reduce the risk of inadvertent access to data by making it difficult for app developers to gain full access to user’s Google Drive account. Their recommended access is to only allow apps to access files that the app created. With this, they have also changed the way the apps are verified for allowing such broad access to Google Drive. We are working thru the process of getting the verification completed, as it involves other third party companies, other than Google.

During this process, Google has marked our app as unverified. If you’ve been using our apps with full access to Google Drive, you may get a warning from Google that the app is unverified. You can remove the app’s full access to Google Drive and then log in to Google Drive again in the app by selecting the “limited access” option that only allows the app to access its own files. It is a much safer option in terms of access to your data on Google Drive and is the recommended option from Google. This is also the new default option in the app.

You may also want to read thru information about app not seeing some files and folders after the access level is changed.