For those who don't want to root the phone, you can still avoid most of the ads by using a filtering DNS server with the Private DNS functionality on stock Android ROMs (or only at browser level if your favorite browser support DNS over HTTPS).

It comes with some minor usability issues with captive Wifi portals sometimes, but the trade-off of not having ads in app or while browsing is way worth it IMHO.

You can use RethinkDNS and avoid compatibility issues with captive portals. This is one of the options we recommend for GrapheneOS users. RethinkDNS is implemented as a VPN service but it has support for local filtering combined with optionally using a WireGuard VPN or multiple chained WireGuard VPNs. Android's captive portal handling works with a VPN and VPN leak blocking active since the connectivity checks are specially marked as not going through the VPN and so is the captive portal handling component opened by the captive portal notification. Private DNS is still missing support for this and also has the issue of causing DNS leaks for secondary profile VPNs.

I put a Private DNS ('controld' for that matter) and never looked back. No more private VPNs with Blokada, no more block list updates. You choose if you want ad, tracker or adult blocking, without hassle, for free.