I am developing an Android Pixelfed client and I have a problem. When the user chooses to authenticate using Sign-in-through mastodon, the internal browser used for the login process is not closed and the "Do you want to authorize this app"-screen is never shown. The user would have to close the browser and click again on the login button to finish the oauth process. If they do that, the authorization screen still is not shown and it will be accepted automatically.

If the user chooses to login with pixelfed credentials (just the normal login, no fancy mastodon stuff), everything works correctly.