Suggestion* Killswitch for VPN when VPN is disabled

Can anyone tell me how I would use / modify this command to work on openwrt 23.05 since the custom tab isn't present from within the firewall. I believe this a result of going from iptables to nftables.

EDIT:

I have placed the command in the startup as described here:

Is there a better way to implement / convert to nftables?