uinerface is not a valid option for dnsmasq - a typo?
Does it read interface=tun0 instead?
With only these lines, your VPN would not be operative, as now tun0 is missing.
If your custom 02-ovpn.conf contains interface=tun0 as noted above, that should make up for a working configuration.
I also just noticed that this post is basically a reincarnation of your last year's Pihole DNS on RPI does not resolve from Windows, not from RPI address, works through piVPN, where an equivalent solution was proposed. 