In 2020, the lab-leak theory was specifically being promoted by people who were advancing the idea that Covid was a) an engineered bio-weapon b) required a national security response in lieu of a medical one.
But if we really want to look back at 2020-2021, there were MUCH more egregious examples of "experts" wielding their credentials maliciously. School closures I think will be the most pertinent example for a while to come.