That’s right, NS.
T means truth. It’s morphed from Spill the T to Spill the tea.
It’s come from drag and trans culture.
In John Berendt’s 1994 novel Midnight in the Garden of Good and Evil - which is both a very good story and made into a very good film starring John Cusack, Kevin Spacey and Jude Law - the real-life character Lady Chablis uses T for truth.
In her autobiography, Hiding the Candy, she writes of ”callin' it out and pourin' the T!" meaning she was speaking the raw, honest truth about her life and the people around her.