dig +trace reveals that only some of the nameservers don't respond (on IPv4, but got a fine response after trying an IPv6).

    ;; communications error to 66.111.50.12#53: timed out
    ;; communications error to 66.111.50.12#53: timed out
    ;; communications error to 66.111.50.12#53: timed out
    ;; communications error to 66.111.48.12#53: timed out
    whatsapp.com.  60 IN A 157.240.223.60
    ;; Received 57 bytes from 2620:13e:100d:c::35#53(d.ns.whatsapp.net) in 119 ms

Especially a.ns.whatsapp.net still seems down (IPv6 also).

I wonder whether this could be a BGP thing again, it was modified very recently according to [1] but I don't understand too much about that.

[1] https://lg.twelve99.net/?type=bgp&router=bei-b2&address=66.1...