I use NextDNS, which others have mentioned here.
But Mullvad also has public DNS (DoH and DoT only).

It’s not an ad blocker in the way you expect something like uBlock to work, if that’s what you’re asking. Get Pihole or AdGuard on your network and use that. VPN when mobile if you’re super paranoid.

It’s just a dns server. You need to use Firefox with its tracking protection and plugins like ublock origin.

Or you can use a dns based ad blocker like pihole so all your devices on your home network is protected.

Then if you are like me, you set up a wireguard server at home, and configures your phone to use that as an always on VPN. And then your phone is also protected by your pihole even if you are away from home and using 3g/4g traffic.

Check out nextdns or quad9. Though, on mobile, I would look into using a vpn like mullvad or protonvpn, they have malware and ad blocking built in too. I prefer this method because I use school wifi a lot and they force their google dns on the phone so I can’t use nextdns or quad9, vpn will get around that and filter your traffic.

Look into next dns maybe

Expounding on previous suggestions…

“On iOS” is rough because you’re at the mercy of whatever incredibly limited experience Apple allows. Safari is the only real browser on your phone and it can be subjected to limited ad blocking, followed by your system (phone or tablet) with something like AdGuard.

If you’re on a particular home WiFi network, you can also add your own DNS filter using something like PiHole.

Use NextDNS with this guide:

https://github.com/yokoffing/NextDNS-Config

Haven’t had anything broken :)

It’s okay, but I’d personally recommend NextDNS more. Quad9 is also good, but more basic.