I believe that once I have pihole + unbound set up I should only see one IP address (my IP) when using a DNS leak test like https://www.dnsleaktest.com/
Actual Behaviour:
However I see a few IP addresses belonging to my ISP, in addition to my own IP, is it possible they are hijacking certain requests? Is there any way to test for this and to stop this from happening?
I can see from the unbound stats that it is indeed processing DNS requests.
TLDR; comment out the unbound entry in /etc/resolvconf.conf, however, if resolvconf managed to run with the entry active , it creates a file /etc/unbound/unbound.conf.d/resolvconf_resolvers.conf. You need to delete that file and restart unbound to resume normal behaviour.