I can't edit this anymore, but further down in this thread it turned out that it's just systemd that refuses to attempt a global DNS A lookup for a single-label name, so this record DOES still exist, just like it ever did, but all the machines that I've tried on for the past few years as well as yesterday were Linux systems using a local systemd stub resolver that enforced this rule. :-(

I guess I should get some servers running other operating systems, or something.

It might be difficult to convince the systemd developers that this special case should be removed just because of this one anomalous DNS name...