It's an open secret that this is a problem everywhere, not just medical regulation. The revolving door was once an issue that the left campaigned on, in fact, but you don't hear much about it any more. Probably because there's no obvious fix beyond ensuring that pay for regulators keeps up with whatever comp the private sector is willing to offer, which is the sort of solution that's not politically popular on that side of the aisle. Also it's hard. The value of less aggressive regulation to companies like Pfizer is very high. Governments meanwhile are ideologically optimized to hire more people at lower wages, not fewer people at higher wages. The whole culture of pay more to hire the best that you find in places like the tech industry just doesn't happen there, and in the USA there's even a rule limiting pay to be lower than the President (which mysteriously doesn't apply to Fauci, wonder how that one works).

You could also try hacks like laws forbidding regulators from (re)joining the industry they regulate, but that'd just make the job even less attractive and ensure that whoever the government does end up hiring are the industry rejects, who will either have an axe to grind or simply not be able to keep up with the technical issues, making them easy to bamboozle.

There's not really a great solution here, beyond maybe just being realistic about what government regulation is capable of. Private sector regulators is also a possibility. Uber is a taxi regulator of sorts, but a much more effective and innovative one, and one whose staff can't be bought off with the carrot of luxury jobs in the taxi sector.