But, yeah, at some point in the 90s, Massachusetts decided to release some "anonymized" health records for research purposes (I think just state employees). One was governor William Weld who obviously had a lot of public information widely available. As I recall, Sweeney wrote the governor's office a bit later basically saying "I have your medical records."
I used this as a slide or two in some AI presentations in the mid-2000s or so pre-LLMs when I had some peripheral involvement with some of the privacy-preserving research going on (differential privacy, multiparty computation, fully homomorphic encryption). Haven't really followed most of this for a while.