Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Avoid the indefinite use of they, it, and you
Make pronoun references clear
Grammar

Do not use the pronoun they to refer indefinitely to persons who have not been specifically mentioned. They should always refer to a specific antecedent.

The word it should not be used indefinitely in constructions such as It is said on television . . . or In the book, it says that . . .

The pronoun you is appropriate only when the writer is addressing the reader directly: Once you have signed the form, return it to your adviser. Except in informal contexts, you should not be used to mean “anyone in general.” Use a noun instead.