com/istio/istio/issues/13739>Issue 13739</a>).</li></ul><h2 id=small-enhancements>Small enhancements</h2><ul><li>If access logs are enabled, <code>passthrough</code> listener requests will be logged.</li><li>Make Pilot tolerate unknown JSON fields to make it easier to rollback to older versions during upgrade.</li><li>Add support for fallback secrets to <code>SDS</code> which Envoy can use instead of waiting indefinitely for late or non-existent secrets during startup (<a href=https://github.com/istio/istio