The api.nextdns.io endpoint, which streams out per-user analytics and query logs among other things, is hosted on (or has something to do with) Google Cloud.
The website itself is on Vercel (which inturn is on AWS) and Cloudflare.
So, if you’re wanting to stay away from BigTech, NextDNS isn’t it.
Don’t email them, as their support, by all indications, is on Google Workspace, as well.
NextDNS does not mention about their use of BigTech in their “sub processors” privacy policy. And to the best of my knowledge they have never confirmed anything one way or the other.
What they’ve got going for them are their fanbois who get very abusive on reddit and elsewhere (: Good thing is, it is easy to avoid them. They aren’t here… yet.