All you have to do is read these two papers. It's where everyone gets their "evidence of harms" about kava from. Even this google result goes back to Mathews flawed conclusions. I believe, after all my research so far, that the core of the problem with society and kava draws back to these two studies and the horribly documented adverse reports of the early 2000s.
Butt, Julia. 2019.
Kava Usage in Aboriginal and Pacific Islander Communities in Australia. National Drug Research Institute.
and
Mathews, J. D., M. D. Riley, L. Fejo, E. Munoz, N. R. Milns, I. D. Gardner, J. R. Powers, E. Ganygulpa, and B. J. Gununuwawuy. 1988. “Effects of the Heavy Usage of Kava on Physical Health: Summary of a Pilot Survey in an Aboriginal Community.”
The Medical Journal of Australia 148 (11): 548–55.
https://sci-hub.se/10.5694/j.1326-5377.1988.tb93809.x