Nassim Taleb popularized, in the mid to late 2000's, the concept of an actually unforseeable risk, that there was absolutely no way to price in to any risk assessment models, because it was a totally unprecedented occurrence, a thing that legitimately had never happened before, that could not be forseeable as possible given prior history/knowledge that you have access to.
Based around the idea of I think some European explorers being totally flabbergasted upon seeing the first black swan that they'd ever seen, their entire previous experience and culture teaching them that swans were always white.
The entire idea was that these kinds of things do actually happen, historically, with fairly decent regularity.
But, a whole bunch of people who I guess just skim-read Taleb's writings... just took a 'Black Swan Event' to mean 'something very uncommon'.
... Which is missing the point entirely.
Because 'something very uncommon' very often is something that is considered, is modelled in as a possibility (just a low possibility) in risk evaluation models.
A Black Swan Event on the other hand is supposed to be something that escapes that, that could not even exist as any kind of a possibility in your risk model.
Basically, if I can run through a list of assumptions your risk model makes, and then describe scenarios where those assumptions are broken, and how that changes your risk model... those aren't really Black Swan events, especially if I can also model the chances of your assumptions being wrong, based on ... you know, other times those kinds of assumptions have turned out to be wrong, in the past.
Consider the insurance/legal concept of 'an act of God'.
Its... not literally meant to mean an actual act of God, its meant to mean something out of any involved party's direct control.
... But you can still build entire sophisticated risk models based around the likelihood that 'God' will do a particular thing at a particular point in time.
The phrase Black Swan Event was invented to try and convince people that they should probably be double checking their investment/insurance strategies, should probably lower their overall risk appetite compared to what existing models tell you it should be, that people should be more conservative with money, have backup/contingency plans, because those models often, provably, fail to appreciate or understand or imagine hitherto unprecedented events.
But, a bunch of morons just started using the term as an excuse for themselves when things happened that they did know were possible, just didn't think were likely.
Or, as an excuse for things that... fairly easily could be modelled, if they had done proper underwriting, used more comprehensive, already existing metholodologies... but well that's hard and takes time and involves more work!
The exact opposite of what Taleb was trying to get people to do.
Consider the recent massive downward revisions to job gains numbers by the BLS.
... Downward revisions to initial jobs reports happen all the time, very common.
Its uncommon that they happen to such a great magnitude...
But... its modellable, literally just based on the history of BLS reports themselves, not even comparing to other data sets.
But but! ... Most people don't pay any attention to the revisions, they just go with the first initial report, don't bother to keep track of the growing, rising innacuracy of initial vs final/revised jobs numbers.
Then, when you do what risk modellers are supposed to do, and take in as many indicators, as much useful.data as you can from other sources... well, you actually can find patterns that strongly indicate when such an error is likely currently occuring in your one data set (BLS jobs) that doesn't seem to match all the other ones.
(If you're even like a professional at this or something, you'll deep dive into the precise methodology of how such data is gathered, to essentially audit it.)
People who want to believe the fairly tale act surprised and make excuses, while people like me have been making the argument that ... yeah the BLS numbers are crap... before they were revealed as such.
Thus... not a black swan event.
In fact, a very expected event... if you remain skeptical and diligent, are aware that no one is immune to propoganda, hype, FOMO, etc.