“Both teach division of the godhead. (heretical)”
I’ve noticed that most Jews give their fellow Kabbalists a pass. You are aware that Kabbalists believe the godhead is divided into ten sephiroths aren’t you? Are you prepared then to call them heretics?
The connection of Kabbalism with Gnosticism is quite obvious. There is evidence that the form of Gnosticism that nearly destroyed Christianity in the early centuries came from Kabbalist Jews. The leaders of early Gnostic Christian schools were Jews.
If anyone divides the singular G-d into 3 personages or 10, yes, I would call them heretical.
A true Kabbalist is not doing that. The 10 Sephirot are attributes not persons or divisions of G-d.
That is why amongst Judaism, study of Kabbalah is recommended only after the age of 40 and that assumes a person has studied Torah already since childhood.