Sexy Sadie is about the Maharishi.

Yes. John Lennon wrote it after getting disillusioned with Maharishi Mahesh Yogi during that trip to India. The original title was literally “Maharishi” — they changed it to avoid a lawsuit.

The lyric “Sexy Sadie, what have you done? You made a fool of everyone” was aimed at the guru. Lennon felt the Maharishi was more interested in fame and women than enlightenment. The song is essentially a bitter, sarcastic goodbye.

The other famous song from that India trip, “Dear Prudence,” is about Mia Farrow’s sister, not the Maharishi. So if someone asks which Beatles song came from a conversation with him, it’s “Sexy Sadie.”