"Sign in using Google" button opens in Custom Tab, breaks login flow

Followed the example in this repo and made an extension with google sign in flow. It works when I work on it locally. After uploading it to the web store and testing it the button sends me to a new tab and then reloads it and stays focused on it. That creates a loop that you can't break out from and the only way to get out of it is to uninstall the extension and force quit Google Chrome.