Google Sign-In blocked in Calendly when opened via Tasker in-app browser (WebView user agent)

Environment

• Platform: iOS 26.2 iPhone 14 pro
• Application: Tasker (iOS)
• Feature: Open external link / in-app browser (WebView)
• Third-party service: Calendly
• Authentication provider: Google Sign-In
• Account type: Google account (gmail.com)
• Error code: 403 – disallowed_useragent

Steps to Reproduce

1. Open Tasker app on iOS.
2. Trigger an action that opens a Calendly link inside Tasker’s in-app browser (WebView).
3. Click “Sign in with Google”.
4. Select a Google account.

Actual Result

• Google blocks the authentication request.
• Error message displayed:

“Access blocked: Calendly’s request does not comply with Google’s ‘Use secure browsers’ policy”

Error 403: disallowed_useragent

• User cannot authenticate via Google inside Tasker.

Expected Result

• Tasker should open Google authentication in a secure system browser (Safari / ASWebAuthenticationSession).
• Google Sign-In should complete successfully, as it does when:
• Opening the same Calendly link directly in Safari
• Opening the same link in Chrome