I agree that C-rating is not correct, but it should still have high current.
It’s strange that you were able to pull only 100A out of your lipo. I don’t think that the lipo was limiting factor, because if you short the battery, even small 1500mAh lipo will give you over 200A. Of couse pulling this current will permanently damage the battery, but it is possible.
Thanks for sharing your experience, I though that lipos can handle high current without a problem. Discharging battery in 5 minutes means that you were pulling 12C on average, meaning 120A on average. That battery was most definitely false labeled. Lot of cases where there are different specs written on the wrap than on the cells when you take the wrap off.