In a deeper sense, I feel like there's also a growing desire to express vulnerability, and so hearing people talk more openly about this stuff doesn't mean it's a trend or that it's invalid in some form, it's instead bucking the trend of dealing in silence.
The truth would sit somewhere between those angles.
IMO it is a defense mechanism (as is having unchallenged confidence). Claiming you have imposter syndrome is a way people with a 'fixed mindset' to avoid confronting harsh realities.
Whenever they make a mistake or lack knowledge in something, their whole identity of being an expert, high performing individual or "winner" gets challenged and they experience a loss of their identity. Claiming imposter syndrome is an extremely self-indulgent way to keep their positive identity in tact by rationalizing that their bad feelings in light of failure are somehow false and that all competent people feel the same way. In some ways, someone with arrogant, unwarranted confidence is doing the exact same thing in a different way.
The original sin so to speak is tying success to one's identity instead of viewing it as the multivariate and stochastic process that it is. In order to achieve a goal or a result, you will necessarily have to be thrown into foreign situations where you know close to nothing and start off as a beginner. The outcome doesn't care about your self-righteous "imposter syndrome", you either get the thing done or get someone else to get the thing done. If this involves being humble and studying something, do it. If it involves putting your ego aside and deferring to people who demonstrably know more and learning from them, do it. This calculus has no space to cry about imposter syndrome.
The people who harp on and on about imposter syndrome are more likely to justify insecure behaviors that don't move you closer to the end result in my experience. To iterate, the end result doesn't care about your feelings or self-identity, develop a growth mindset and focus on achieving the outcome in the most effective way possible instead of worrying about who is an "imposter". If you fail at a job and are unable to deliver, there are many factors at play, most of which were already probably predetermined before you accepted the role. The best thing you can do if you find yourself in this situation is to fix it instead of behaving defensively.
and who cares if your work environment or your boss or is bad. you either worked hard enough or you didn't. if it were me, i would have simply worked hard enough to overcome such challenges