I suspect this really screws with the DNS tricks used by many CDNs to route requests to near-by servers. So I would not be surprised if, when using this, YouTube, Netflix, etc, get much slower.
Prior to this, I was running Intra [0] on my Android phone to route all DNS traffic to cloudflare-dns and had been pretty happy to use it in tandem with PrivacyBadger, uMatrix, and uBlockOrigin on Firefox.
Someone suggested using AdAway [1] on rooted devices and another app that does a similar trick of running a local VPN on Android through user supplied hosts file. Great alternative.
We embed ECS data in our requests at DNSFilter to the authoritative upstreams, and we have a large global anycast network, so even if they're not accepting it, the answer is coming from a server 'nearby' the originating dns request, so CDN requests shouldn't be affected much.