Facebook login as custom provider not working

**Describe the bug**

Following the directions for Facebook login at https://learn.microsoft.com/en-us/azure/static-web-apps/authentication-custom?tabs=facebook leads to Facebook error page: "Feature Unavailable/Facebook Login is currently unavailable for this app." which leads to "The domain of this URL isn't included in the app's domains. To be able to load this URL, add all domains and subdomains of your app to the App Domains field in your app settings."


then when you click OK, it goes to


A clear and concise description of what the bug is.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to https://dungeondraw.shiningsword.org/
2. Click on "Login" and then "Facebook" in the upper-left corner
3. Observe error

The Facebook app is configured according to Azure Static Web App [documentation for custom auth providers](https://learn.microsoft.com/en-us/azure/static-web-apps/authentication-custom?tabs=facebook) (AppDomain and redirect URI, plus a few other redirect URIs just in case), but apparently the redirectUri of https://identity.2.azurestaticapps.net/.auth/login/facebook/callback is causing Facebook to reject the request anyway.


**Expected behavior**
I expected the static web app to work the same way with Facebook as it does with AAD, which in this case would just print the user's name in the top-left:


**Device info (if applicable):**
- Browser: Chrome

**Additional context**
I suspect this is actually a Facebook issue and I filed a bug at (https://developers.facebook.com/support/bugs/1317495038787988/), but they seem at a loss what to do about an app that isn't using Facebook's own JavaScript SDK to log in. In particular they seem surprised that Azure Static Web Apps specifies **redirect_uri=https%3A%2F%2Fidentity.2.azurestaticapps.net%2F.auth%2Flogin%2Ffacebook%2Fcallback** in the HTTP request.

If this is something that Azure Static Web apps can fix, I would like to know it; if it is something that is impossible for now, I would like the documentation at https://learn.microsoft.com/en-us/azure/static-web-apps/authentication-custom?tabs=facebook to be updated to say it's impossible. If I'm the only one who encounters this issue I would like to know that too.