I do the same in opnsense. According to dnsperfbench, running my own resolver benchmarked as slightly faster or at minimum about the same performance as using any of the big public resolvers. I think the only concern is to make sure you’re not using your local resolver if you’re trying to use a VPN.

If I understand correctly, every sync feature that requires the subscription (and cannot be purchased by a one time fee) requires the sync dev to run a constantly online server. Translation makes calls to translation services that cost money, push notifications require a push server since Lemmy servers don’t include support for it, etc. Removing ads doesn’t cost sync ongoing cash which is why you can get it for a one time fee.

Seems reasonable to me.