As I went school in S.Korea, English teachers never pronounced voiceless labialised velar approximant [ʍ] and even regarded that as taboo(they teach American English). But when I took TOEFL test, the narrator pronounced 'what' as [ʍɑːt].

For now I study linguistics, and learned from lessons that [ʍ] is sometimes pronounced by old people in America while young people don't; which was actually originated from Old English 'hw-'[ʍ] and remains in many words⁠why, whistle, what (Old English hwon, hwistle, hwa).

Is it quite common to pronounce like that?