@dalto, you helped me to setup a killswitch for my vpn with ufw rules here.
ufw status verbose
Status: active
Logging: on (medium)
Default: deny (incoming), deny (outgoing), disabled (routed)
New profiles: skip
To Action From
-- ------ ----
Anywhere ALLOW OUT Anywhere on tun0
192.168.50.1 ALLOW OUT Anywhere
1194/udp ALLOW OUT Anywhere
Anywhere/ipv6 DENY OUT Anywhere/ipv6
Do I need to enable the firewall in OpenSnitch as well?