At least when using direct grant connect flow, the auth_time seems not provided. [1], The iatthe `auth_time` is not present in the decoded_token.
Which fails the conversion to OIDCUser.
The "iat" key is provided though. so fallback to use it [2]
Related to T2858
Related to P975
[1] Related to P975
[2] https://github.com/keycloak/keycloak-documentation/blob/master/server_development/topics/action-token-spi.adoc#anatomy-of-action-token