There is a popular misunderstanding that C.G. Jung approved of Isabel Briggs Myers’ work. However, he repeatedly objected to the popular interpretation of his book Psychological Types and research based on the MBTI® instrument. There was a rift between I.B. Myers and C.G. Jung which has been hidden for more than half a century from those who use Myers-Briggs typology (Myers, S. 2019).
The misunderstanding is largely due to a complimentary letter from Jung to Myers in 1950. However, Jung did not write it and it did not represent his opinion. It was written by his secretary who couched it in diplomatic language to conceal Jung’s disapproval.