This is exactly what the AGPL was made to combat against. But open source devs still choose more permissive licenses first - presumably to attract corporate clients to use their product (and because devs are suckers to large corporate interests)
Because it’s written in C# and relatively new. Unbound is written in C so should consume less resources, has been around longer and has been vetted – FreeBSD and OpenBSD replaced BIND with Unbound.
The one downside to Unbound is that there’s no GUI so it can be a bit intimidating to set up. But the docs are excellent and Unbound defaults are secure, so it’s not as hard as it seems.
The real eye-opener is when you start redirecting DNS 53 requests to your own DNS server and block DoT/DoQ/DoH – so many devices/apps just trying to reach out to their hardcoded DNS servers for tracking/ad targeting.
Doesn’t work for YouTube ads – they no longer load ads via DNS and instead embed them directly into the video feed.
Ublock origin via the browser is the best way to block them. If you wish to use a client app, best bet is to sideload a 3rd party app like like SmartTubeNext for Android TV or YTLitePlus for iOS.