Working in data science I can safely say that that vast majority of people who feel like that have impostor syndrome at the very least really don't know what they are doing. A true imposter theoretically knows they don't know enough, and wants to get away with it. I think it's fair to say people with "impostor syndrome" aren't truly malicious impostors.. but there is this frequent assumption having "impostor syndrome" means "I actually do know what I'm doing".
I find the real issue is that being an expert no longer matters in most roles, so true experts increasingly have disappeared except in a few, mostly academic or skilled trade areas.
This is glaringly obvious in data science where I have been to many large, respectable companies where nobody understands any of the real fundamentals of what they're doing. It's just a bunch of automatons feeding data they don't understand, into models they don't understand, to be used in products they don't understand. But it's ridiculous to blame individuals for this. This is so pervasive in the culture that I have often found myself needing to guess which incorrect or not quite right answer to give in job interviews.
People working at places like this are right to feel that they don't know what they're doing, because they rushed through a boot camp to learn the basics and stopped there. At the same time they shouldn't feel like impostors because they aren't succeeding from some malicious intent, but because the system is broken. Most of them are dying for an expert to give them advice, but because of the broken system this is impossible.
It's not just tech either. We see this in "skilled" trades (to be clear, the quotes aren't because I don't believe these trades require skill, but because they have been transformed into something that increasing does not... even when it should). Plumbing for example used to be a field where it was a big deal to have connections with an experienced, expert plumber who could correctly solve your problem. Currently most "plumbers" are giant companies with a few real plumber's having their "assistants" who can hardly tell a leak from a faucet looking perplexedly at the drip in your ceiling take care of all the calls.
If you really care about knowing something today, the burden is all on you to learn it and there will be no reward other than your personal satisfaction. It may even cause you hardship from time to time when you have to pretend you don't understand something to do your job in a satisfactory way.