While trying to open or login to an iOS app, you may receive the following error message which prevents you from accessing the app.
403. That's an error.
This user-agent is not permitted to make an OAuth authorization request to Google as it classified as an embedded user-agent (also known as a web-view). Per our policy, only browsers are permitted to make authorization requests to Google. We offer several libraries and samples for native apps to perform authorization request in the browser.
This is a problem the app developer will need to fix and address. The application you are using is trying to make a login request but is not being identified as an authorize browser agent (or is now using a depreciated bowser agent). You will need to let the app developer know this directly The app developer can use GTMAppAUth instead.