[throwaway77385]

To report back on this, I contacted the various email addresses given in OP's article.

For people with GDPR rights, this link helps make a DSAR (though interestingly the US and many other countries are also available from the country dropdown, maybe they follow these rules everywhere): https://withpersona.com/dsar

This of course brings up the problem of having to verify the ID of the person who's requesting their ID to be deleted from their DB. So I am probably going to stop here.

I also received a separate email stating that my data was already scheduled for deletion if I used Persona through LinkedIn.