I realized upon reading too this was the same Danfoss fridges that got hit for .mil bases in the US. There's probably a shodan signature to find them on the internet because HVAC people don't know about network security, and someone has a trivial exploit to access them due to shitty ancient embedded controller security in them.

This was precisely my first thought upon reading. "Ah, yes - the attack that was PoC'ed against commissaries operated by the US armed forces a bit over a month ago."

Yeah I remember that, and it seems like the military was very hush-hush about the cause. Now I wonder if they were hacked too.

Yes, not exactly "unprecedented." The news of Commissaries having their freezers hacked should have been a kick in the rump for everyone else with infrastructure needlessly connected to the Internet.