ICMPv6 over lo0

Dear all,

when using the master branch of today (or 13.1) I get when running

tuexen@ampere128:~ % ping6 -c 1 -b 30000 -s 20000 ::1
PING6(20048=40+8+20000 bytes) ::1 --> ::1
20008 bytes from ::1, icmp_seq=0 hlim=64 time=0.709 ms

--- ::1 ping6 statistics ---
1 packets transmitted, 1 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 0.709/0.709/0.709/0.000 ms

which is expected. What I don't expect is:

tuexen@ampere128:~ % tcpdump -i lo0 -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo0, link-type NULL (BSD loopback), capture size 262144 bytes
22:06:38.835630 IP6 ::1 > ::1: frag (0|1232) ICMP6, echo request, seq 0, length 1232
22:06:38.835639 IP6 ::1 > ::1: frag (1232|1232)
22:06:38.835641 IP6 ::1 > ::1: frag (2464|1232)
22:06:38.835641 IP6 ::1 > ::1: frag (3696|1232)
22:06:38.835642 IP6 ::1 > ::1: frag (4928|1232)
22:06:38.835642 IP6 ::1 > ::1: frag (6160|1232)
22:06:38.835643 IP6 ::1 > ::1: frag (7392|1232)
22:06:38.835644 IP6 ::1 > ::1: frag (8624|1232)
22:06:38.835644 IP6 ::1 > ::1: frag (9856|1232)
22:06:38.835645 IP6 ::1 > ::1: frag (11088|1232)
22:06:38.835645 IP6 ::1 > ::1: frag (12320|1232)
22:06:38.835646 IP6 ::1 > ::1: frag (13552|1232)
22:06:38.835647 IP6 ::1 > ::1: frag (14784|1232)
22:06:38.835647 IP6 ::1 > ::1: frag (16016|1232)
22:06:38.835648 IP6 ::1 > ::1: frag (17248|1232)
22:06:38.835648 IP6 ::1 > ::1: frag (18480|1232)
22:06:38.835649 IP6 ::1 > ::1: frag (19712|296)
22:06:38.836002 IP6 ::1 > ::1: frag (0|16336) ICMP6, echo reply, seq 0, length 16336
22:06:38.836006 IP6 ::1 > ::1: frag (16336|3672)
^C
19 packets captured
19 packets received by filter
0 packets dropped by kernel

Why is for the Echo Request an MTU of 1280 used, whereas for the response an MTU of 16384
is used.

Since
tuexen@ampere128:~ % ifconfig lo0
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
	options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
	inet6 ::1 prefixlen 128
	inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
	inet 127.0.0.1 netmask 0xff000000
	groups: lo
	nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
is used, I would expect an MTU of 16384 also be used for the Echo Request instead of
the minimum IPv6 MTU of 1280.

Is this intended? At least for me, it is not expected...

Best regards
Michael