Slower routing of the DNS traffic

Hello good people of NextDNS, when running a test on https://ping.nextdns.io I see there are many faster servers than the selected one, Is there a reason or a methodology behind that? I mean based on what the server is chosen? the protocol, latency, geographical location ...etc

I'm using DoH through the browser settings of Firefox, please let me know if you need any addition information.

Also is there a way to manually choose a closer server by specifying the server in the endpoint?
 

  anexia-waw         1 ms  (anycast2)
  zepto-waw          1 ms  (anycast1)
  worldstream-tbs   21 ms
  hetzner-tbs       33 ms
  edgeuno-ist       54 ms
■ premiumrdp-tlv    70 ms  (ultralow1)
  netshop-nic       73 ms
  citynet-cai       78 ms
  anexia-tlv       105 ms  (ultralow2)
  lightnode-ruh    105 ms
  edgeuno-ruh      107 ms
  anexia-dxb       131 ms
  edgeuno-cai       error
  zepto-ist         error