Nomad failing iptables command when starting task

I just found that Nomad seems to be executing a iptables command when starting a task which uses an invalid option flag.

When the task starts I get this error in the Nomad UI:

failed to setup alloc: pre-run hook "network" failed: failed to configure networking for alloc: failed to configure network: plugin type="portmap" failed (add): unable to create chain CNI-HOSTPORT-SETMARK: running [/usr/bin/iptables -t nat -C CNI-HOSTPORT-SETMARK -m comment --comment CNI portfwd masquerade mark -j MARK --set-xmark 0x2000/0x2000 --wait]: exit status 2: iptables v1.8.8 (legacy): unknown option "--set-xmark" Try `iptables -h' or 'iptables --help' for more information. 

I’ve tried downgrading iptables from 1.8.8 to 1.8.3 where it seems that the flag exists, but the error persists.

I’ve also checked that my kernel modules are loaded:

❯ sudo lsmod | rg iptable
iptable_filter         16384  1
iptable_nat            16384  1
nf_nat                 57344  2 iptable_nat,xt_MASQUERADE
iptable_mangle         16384  0
ip_tables              36864  3 iptable_filter,iptable_nat,iptable_mangle
x_tables               57344  8 xt_conntrack,iptable_filter,xt_addrtype,xt_comment,ip_tables,iptable_nat,xt_MASQUERADE,iptable_mangle

I’m on Arch Linux running Nomad 1.4.3 and this just appeared today out of nowhere.