Blazor and Cognito

trying to get a blazor server app to authenticate against cognito using Blazor.Auth0

user pool is working (can log in with the hosted ui) but when i run the app i get error 400 and the url shows

https://domain.auth.us-east-2.amazoncognito.com/error?error=redirect_mismatch&client_id=MYCLIENTID

when i use the hosted ui it calls my callback gets redirected to https then calls authorize on the oauth2 domain and then calls/shows the domain above

sure something simple is just not configured correctly. any tips on what to look for?

any help greatly appreciated

Mike