Could be a routing issue (this things need to be tweaked over time). Can you talk to us via the chat on the website so we can debug?

468ms in the UK.

9ms on Cloudflare, 10ms on Google.

There seems to be some routing oddities going on. I'm also in the UK (on AAISP). Sometimes I get ~48ms response, other times 200-300ms.

Looking at mtr I'm occasionally routed to Dallas, Texas. Other times it's correctly routing over my ISP's peering to Vultr.

What command did you run in mtr to see the routing locations?

Or just a normal report, then lookup the IP location?

By default mtr will do reverse DNS lookups on all hops. Several of the traces I ran showed the route to nextdns's /24 transiting over NTT and from the DNS name you can figure out where each router is.

273msec in DC