This was originally going to be a graphical demonstration of how LED efficiency goes down with increasing current, but instead it turned into an intriguing and then annoying graphical representation of how duff LEDs behave with increasing current.
There's a strong possibility that the manufacturer knew this was a duff LED, since it was supplied in a PIR activated fixture (low duty cycle) with a 3W driver instead of a 10W one to reduce the stress on the already defective LED even further to try and extend it's unpredictable life beyond the already non-existent warranty period.