Maybe the parameter you are talking about is redirect_uri, not return_uri. See here for more details about this parameter.
This is the standard OAuth2 parameter that you should use when talking directly to the authorization server, i.e. your Auth0 tenant in this case.
If your Blazor WASM application follows the architecture I discussed in this article, the authentication/login endpoint is not an authentication server (i.e. Auth0) endpoint. It’s the endpoint of a page in your application (specifically, Client/Pages/Authentication.razor).
So, the redirect_uri parameter is ignored. The page relies on the default behavior of the <RemoteAuthenticatorView> component to interact with the authorization server. In this case, you have to use the returnUrl parameter with a fully qualified URL.
In other words, your link should look like the following:
You can’t just use any URL as a returnUrl. It must have the same origin as your application.
Also, if you put Google’s home page as the value for returnUrl, the login process shouldn’t even start, so I don’t understand when you say “When I land on the google account selection page…”
Taking my sample project as our reference, the only change you need to make is related to AccessControl.razor. It should have the following highlighted line:
I just put google.com as I didnt want to post my Auth0 audience URL on here.
By “When I land on the google account selection page…” what I mean is when I click the login link, it goes to Auth0 fine, I choose “log in with Google”, it then takes me to my Google account selection screen, and it has