Gateway API support is GA since OCP 4.19. Users of the Gateway API will need a way to obtain certificates for gateway listeners. Upstream cert-manager has (beta) support for Gateway API since version 1.15: https://cert-manager.io/docs/usage/gateway/

Note that this integration is not only for convenience (automated creation of Certificate based on Gateway definition) but is needed in order to be able to use cert-manager to obtain Gateway listener certs via the HTTP01 challenge (the Ingress HTTP01 solver won't work for a Gateway cert, as the Gateway takes over the DNS name over Ingress). See https://letsencrypt.org/docs/challenge-types/#dns-01-challenge for details.

The flag to enable gateway api support in downstream cert-manager build is currently not supported: https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html/security_and_compliance/cert-manager-operator-for-red-hat-openshift#cert-manager-overridable-arguments_cert-manager-customizing-api-fields

and the only option is to go the unsupported path:

  unsupportedConfigOverrides:
    controller:
      args:
      - --enable-gateway-api