"This block was the result of a communication error between Zoom’s domain registrar, Markmonitor, and GoDaddy Registry, which resulted in GoDaddy Registry mistakenly shutting down zoom.us domain. "
replies(3):
Their domain expired because at some level people made some pretty boneheaded mistakes.
Whomever their actual registrar actually was (GoDaddy it seems) stopped pointing the zoom.us nameserver record (NS) at AWS Route 53 which Zoom obviously uses.
% dig +short zoom.us NS
ns-387.awsdns-48.com.
ns-1137.awsdns-14.org.
ns-1772.awsdns-29.co.uk.
ns-888.awsdns-47.net.
.us (and other many TLDs) uses EPP to communicate between registars (MarkMonitor here) and Registry (GoDaddy). It is probably an admin error rather than code[1], some manual approval or other human review workflow for high value domain and someone clicked/filled in the wrong value at GoDaddy or MarkMonitor would be my first guess.
[1] would have been observed and fixed long before today, transfers happen all the time after all