Instagram, Facebook and WhatsApp are down

For Facebook and WhatsApp it looks like a DNS issue, name resolution fails with SERVFAIL:

    $ dig facebook.com

    ; <<>> DiG 9.16.21 <<>> facebook.com
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 23982
    ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 512
    ;; QUESTION SECTION:
    ;facebook.com.   IN A

    ;; Query time: 16 msec
    ;; SERVER: 8.8.8.8#53(8.8.8.8)
    ;; WHEN: Mon Oct 04 17:53:00 CEST 2021
    ;; MSG SIZE  rcvd: 41