Why am I getting a IDENTITY_PROVIDER_LOGIN_ERROR with error=cookie_not_found in RH-SSO?

Issue

• We have integrated RH-SSO with external Identity Provider and at random we are observing following error in the logs

ERROR [org.keycloak.services.resources.IdentityBrokerService] (default task-4) unexpectedErrorHandlingRequestMessage: javax.ws.rs.WebApplicationException: HTTP 400 Bad Request
        at org.keycloak.keycloak-services@18.0.0.redhat-00001//org.keycloak.services.resources.IdentityBrokerService.parseSessionCode(IdentityBrokerService.java:1060)
        at org.keycloak.keycloak-services@18.0.0.redhat-00001//org.keycloak.services.resources.IdentityBrokerService.performLogin(IdentityBrokerService.java:373)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
...............
WARN  [org.keycloak.events] (default task-4) type=IDENTITY_PROVIDER_LOGIN_ERROR, realmId=broker, clientId=null, userId=null, ipAddress=xxx.xxx.xxx.xxx, error=cookie_not_found, identity_provider=oidc