Unexpected configuration in the nftables rules generated by auto-redirect

For the following nftables snippet generated by auto-redirect,
the rule tcp option mptcp exists counter packets 0 bytes 0 drop
maybe an unintended and unnecessary rule, considering the UDP and ICMP context.

        chain output_udp_icmp {
                type route hook output priority mangle; policy accept;
                meta l4proto != { icmp, udp, ipv6-icmp } return
                meta mark 0x00002024 counter packets 0 bytes 0 return
                ct mark 0x00002024 counter packets 0 bytes 0 return
                ip daddr @inet4_local_address_set counter packets 0 bytes 0 return
                ip6 daddr @inet6_local_address_set counter packets 0 bytes 0 return
                tcp option mptcp exists counter packets 0 bytes 0 drop
                meta mark set 0x00002023 ct mark set meta mark counter packets 0 bytes 0 return
        }

Related commit https://github.com/SagerNet/sing-tun/commit/b49e63f8efdbe7071ec0784829833010fbfb4567

Start with the related commit and trace the auto-redirect code that generates the shown nftables chain. Determine whether the MPTCP drop rule is intentional in the UDP and ICMP context; done means the generated rules match the intended protocol behavior and the relevant project checks pass.