Querying 1.1.1.1: TCP is 183 msec, UDP is 323 msec. Querying my local DNS, a pi-hole instance running in Docker on a Synology DSM: TCP is 3 msec, UDP is 0 msec

Querying 1.1.1.1: TCP is 183 msec, UDP is 323 msec. Querying my local DNS, a pi-hole instance running in Docker on a Synology DSM: TCP is 3 msec, UDP is 0 msec (per the dig output). So my initial take is that DNS over UDP is faster on the local network and thus you need to start digging into why Cloudflare is behaving as it is, or maybe there's something with all the hops between you and there. Some transparent DNS proxy or something?