> There's no rule that your DNS server must be on the same network as you, or send your subenet if it isn't.
It's the default configuration. 99% of internet users follow this configuration (at least, until web browsers start shipping DoH as a default). It's honestly a fairly reasonable assumption to make.
>>roblab+(OP)
It's an even more reasonable assumption for CDN latency-minimisation geo-IP/DNS purposes. Even if it's not on the same network, your DNS server is usually on the same continent!
>>roblab+(OP)
Can't you argue the inverse as well? Cloudflare isn't sending EDNS Client Subnet to any other authoritative name servers, is anyone else having problems? Or are 99% of people working just fine without this optional EDNS information? So isn't it archive.is who is the 1% who isn't following the standard configuration? Which is to still resolve correctly even without the option EDNS information? Sure, it might not be the best possible answer for a client, but you can still return an answer?