Yes, leaks with IPv6.
I have IPv6 disabled in all VPN configurations.
Tests on https://ipleak.net/ show different IPs, so for that, it seems to work.
I installed these packages on my XA2 due to a reverse-understanding 
of the subject (https://forum.sailfishos.org/t/4-5-0-18-french-operator-sfr-webradio-no-sound/14877/).
It is interresting to notice than afterwards, I could enable VPN again (was not working well since .18).
If nothing related to VPN was changed, it might be a coincidence or some side effect…