I’ve heard from a Tibetan Buddhist regarding bad karma one should simply observe whatever bad happens to them and accept that past karma caused it. While dwelling and judging would only cause more suffering, you should take it as a sign to commit to the path and do a lot of positive actions for others, which would result in less personal suffering. Bad events and hardships are seen as teachers, not punishment. The only time I’ve heard talk of Buddhists hurting themselves is a monk cutting his flesh to save someone else and it was an example of how to see whether one is nondual because the monk was like “welp, I guess I’m not fully enlightened. This kinda hurts.”

I’ve never heard of that sect but it sounds pretty sketchy and I’m glad you’re out. I understand and am sorry that dampened your perspective on the dharma. I hope your reconsideration is fruitful.