Is this a bug in /usr/sbin/ss?

I am using 12.3 RC1 now. When I executed /usr/sbin/ss -atu, its output had something like this:
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
tcp UNCONN 0 0 *:mdns :
tcp UNCONN 0 0 *:58927 :
I think the Netid should be udp other than tcp.
Is this a bug?
ss --version shows: ss utility, iproute2-ss121211

Kinda looks like it. Here is my ‘–version’ output from 12.2 which seems
to show things correctly:

ss utility, iproute2-ss120521

Perhaps see if the upstream iproute2 package has anything on this and if
not report it. It’d probably also be useful, when reporting this, to show
the corresponding netstat output so that the difference is more obvious.

Good luck.

I compiled iproute2 v3.8.0 from source, but misc/ss -atu still showed the same result. It seems this is an upstream bug. misc/ss --version showed ss utility, iproute2-ss130221.