Hello anonymous user, thank you for reaching out. The Redirect URI is the location where AAD B2C is expected to post the token back once the authentication/authorization is done by AAD B2C and from this location, the app is expected to fetch the token and validate it or use it for its next steps.
Among the two Redirect URIs that you mentioned above, ideally, you can choose and use any one of them, but you need to make sure that the redirect URI is consistent in both places i.e in your code as well as in the app registration in AAD B2C.
Hope this helps.
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