Read this, seems A) rare and B) not clearly due to green tea extract.
The data is basically anecdotal and there isn’t a lot of cases. And none of the cases were due to using green tea, they were herbal mixtures with many ingredients.
It is rare, and is probably due to a combination of green tea and weight loss. However, the effects are catastrophic, and it worth pointing out before someone decides to use tea extracts to "protect" their liver.
There are more cases that appears through cursory review of the literature, as most go unreported/unpublished. I have seen one case myself, and the person barely survived.
The data is basically anecdotal and there isn’t a lot of cases. And none of the cases were due to using green tea, they were herbal mixtures with many ingredients.