AAAA RRs for AirVPN servers

[OpenSourcerer 1435]

Hi there!

Seemingly there are no AAAA resource records returned when querying any DNS server for AirVPN's server IPs:

$ dig any in errai.airvpn.org.

; <<>> DiG 9.11.5-P4-3-Debian <<>> any in errai.airvpn.org.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63963
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;errai.airvpn.org.              IN      ANY

;; ANSWER SECTION:
errai.airvpn.org.       3198    IN      A       185.189.112.10
errai.airvpn.org.       3198    IN      RRSIG   A 8 3 3600 20190512182416 20190427182416 5220 airvpn.org. Bs2dfKKNAWs6TvfjDLIl7WvXiLETD3NmesZrLX8bnYBtGEyrTrum4W6T btSU54u6oAQeArwNH+umxqarXGCKXgTtzy+HPQ9M3g76NqPPCie5rx5B ZCTj1D80D30PrCvICwwQRnaP1sElsQJdyrecrT3rWGB9S+RQSEBbTvzf sac=

;; Query time: 52 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fr Mai 03 19:06:51 CEST 2019
;; MSG SIZE  rcvd: 231

I tried my ISP's DNS resolver, Google's and Cloudflare's Public DNS (which returned a NOTIMP for ANY requests, but didn't return any AAAAs otherwise) on servers with IPv6 support, like Errai shown above.
Is this intended? Did I miss a thread on this in the past? Or am I doing something wrong?