The description of the rc.conf variable ip6addrctl_enable contains the only documentation for the variable ip6addrctl_policy (which is another problem, but I'm not going to open a but report for that).
The description of the ip6addrctl_policy says:
If ``ipv4_prefer'' or ``ipv6_prefer'' is specified, ip6addrctl(8) installs a pre-defined policy table described in Section 2.1 (IPv6-preferred) or 10.3 (IPv4-preferred) of RFC 3484.
A strict reading of this suggests that setting ip6addrctl_policy to "ipv4_prefer" will install a "pre-defined policy table described in Section 2.1 (IPv6-preferred)". The second part of this sentence needs to be reversed so that the correct tables correspond to the correct policy values.
I'll take it.
A commit references this bug:
Date: Mon Sep 9 20:48:12 UTC 2019
New revision: 352107
Reverse the referenced tables.
If ipv4_prefer is specified, Section 10.3 is relevant.
If ipv6_prefer is specified, Section 2.1 is relevant.
This change makes the corresponding options/sections 'respective'
Submitted by: David Fiander <firstname.lastname@example.org>
Thanks, and I'm sorry this trivial change took so long.