see the github issue link here

https://github.com/keycloak/keycloak/pull/7071#issuecomment-634060517

This was resolved in 10.0.2

And I had already mentioned on the article about that

https://medium.com/@karanbir.tech/aws-connect-saml-based-identity-provider-using-keycloak-9b3e6d0111e6 — See Prerequisites point 3