Looking at current git master

In bin/named/statschannel.c

in zone_xmlrender()

in the block:
	zonestats = dns_zone_getrequeststats(zone);
	rcvquerystats = dns_zone_getrcvquerystats(zone);
	if (statlevel == dns_zonestat_full && zonestats != NULL) {
		TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "counters"));
		TRY0(xmlTextWriterWriteAttribute(writer, ISC_XMLCHAR "type",
						 ISC_XMLCHAR "rcode"));

		result = dump_counters(zonestats, isc_statsformat_xml, writer,
				       NULL, nsstats_xmldesc,
				       dns_nsstatscounter_max, nsstats_index,
				       nsstat_values, ISC_STATSDUMP_VERBOSE);
		if (result != ISC_R_SUCCESS)
			goto error;
		/* counters type="rcode"*/
		TRY0(xmlTextWriterEndElement(writer));
	}

paying attention only to the two statements:
		TRY0(xmlTextWriterWriteAttribute(writer, ISC_XMLCHAR "type",
						 ISC_XMLCHAR "rcode"));

		result = dump_counters(zonestats, isc_statsformat_xml, writer,
				       NULL, nsstats_xmldesc,
				       dns_nsstatscounter_max, nsstats_index,
				       nsstat_values, ISC_STATSDUMP_VERBOSE);

Assuming that these stats are emitted, the "counters" container for them is given
a "type" attribute with value "rcode", yet the individual counters will be given
names from nsstats_xmldesc, which does not describe rcodes.

I have not traced things to identify when these stats will be emitted (if ever)
and what the actual contents of zonestats *mean*, but I can say confidently that
/at least/ one of "rcode" or nsstats_xmldesc is wrongfully applied to zonestats,
and possibly even both.