It’s not true. Look.
‘On 10 June 1859, the 19-year-old Tchaikovsky graduated as a titular counselor…”
https://en.m.wikipedia.org/wiki/Pyotr_Ilyich_Tchaikovsky
And for the Tchaikowsky fans, here’s his voice recorded by Julius Block on an Edison cylinder recorder in 1890. Can also hear the deep voice of Anton Rubinstein.
https://www.youtube.com/watch?v=7DEEdFLjUiw