No IPv6 with wwan

Bugs
1

I am using a USB cellular modem (LE910C4-WWXD) on VyOS 2025.04.21-0020-rolling .
It works well enough, but it does not get any IPv6 address.

The main reason seems to be that VyOS sets addr_gen_mode to 1 (“do not generate a link-local address”).

I gather the reasoning for that is because if you put an interface in a bridge, it should not
have a link local address.

However, a cellular modem cannot really be put in a bridge, because the only way it can actually be useful is when the cell network gives an an IPv4/IPv6 address, so this does not seem to apply.

The following two configuration settings (in particular the sysctl one) appears to work for getting an IPv6 address (both link local and global), but it seems a bit kludgy. Should not VyOS always just use 3 for addr_gen_mode for wwan devices? And prohibit putting them in a bridge because it does not make sense?

system {
    sysctl {
        parameter net.ipv6.conf.wwan0.addr_gen_mode {
            value 3
        }
    }
}
interfaces {
    wwan wwan0 {
        address dhcp
        apn ltedata.apn
        description LE910C4-WWXD
        ipv6 {
            address {
                autoconf
            }
        }
    }
}