Google Smarthome oauth account linking is not working

Question

I have implemented an oauth account linking.
If I test it with an old cell phone (Android 5.1) it is working.
On another phone (Android 9) with the same google account it is not working.

What happens:
It calls my auth endpoint.
I redirect to a login page with a google login button.
After the user is signed in, I called an endpoint on my server which redirects to the google redirect uri.
On the phone I see very short that he opens the new web site and then the browser is closed. Nothing further happens.
The token endpoint isn't called.

What can be different between this both phones?
Is there a log where I can see what happens?

With Google Developers OAuth 2.0 Playground the account linking is also working.

Thanks for your help.
Regards Simon

Answer 1

The redirect wasn't working and set of window.location.href to the redirect uri wasn't also not working. The solution is a href with the redircet uri on a new page. A click on this href is working.