What was the restaurant doing wrong? Was it recirculating indoor air? Or was it actually exchanging the air? Replacing indoor air with fresh air from outside.
As I understand it, the restaurant had an air conditioner in front of a table, and an infected but asymptomatic person was breathing into the airstream which was then circulated to infect anyone downwind of the a/c.
The article links to the study. The issue was more than certain people sat downwind of others indoors, rather than where the air came from. Let me know if you read a different conclusion from it.