Why can't my user complete provider auth in the in-app webview?

When a provider login fails inside an in-app webview, ask the end user to open the authentication page in a full external/system browser.

When a provider login fails inside an in-app webview, ask the end user to open the authentication page in a full external/system browser. Most in-app views have a button for this.

Some provider OAuth pages block or misbehave inside embedded webviews, and opening in the system browser typically lets the connection complete.