https://books.google.com/ngrams/graph?content=became+unconscious%2C+lost+consciousness%2C+passed+out&year_start=1800&year_end=2019&corpus=26&smoothing=3&direct_url=t1%3B%2Cbecame%20unconscious%3B%2Cc0%3B.t1%3B%2Clost%20consciousness%3B%2Cc0%3B.t1%3B%2Cpassed%20out%3B%2Cc0

Thanks Uly! The English phrase is real (as I always try to take real English quotes from Google Books, even when adding translations from RU to EN). Now I see it was from a newspaper dated 1905, perhaps they though "to pass out" too vulgar at the time.

Nick, I’m not suggesting it isn’t real, just giving additional information for those who would see your post and add this phrase to their vocabulary without knowing that there are more natural ways to express this. Also, PASS OUT isn’t vulgar in any way. When you see something rate high on Ngrams, it’s because it appears in millions of printed books. If anything, it’s more literary by virtue of its rating on Ngrams.

Oh, I can only thank you for insights, because as a non-native speaker I lose a lot of nuances. I know at IELTS they take points away for using phrasal verbs, and encourage using less colloquial forms - that's what I tried to describe as 'vulgar'

However, ngram, like any stats, should be used with caution.
In this case, all meaning of "pass out" are lumped together, both phrasal verbs and others, so the gap is in fact much narrower than it seems.
Some typical samples for "passed out" from Ngram:
1) In 2001 examination 12 passed out of 28
2) These were also passed out to the two Congolese officers
3) The train passed out of the intermediate box at same time
4) The cotton spinning mill... passed out of existence during the civil war

So phrasal verbs are vulgar too now? It’s like they’re making sure your English is as unnatural as possible. I just don’t understand. Who decides these things?

Not me! :-)

👍🏼😉