Okay, I guess I’ll just have to accept that something is lost in translation. B10 and B50 would normally apply to something that fails completely, like an incandescent bulb. LEDs use something like L70 to indicate lifespan.
I understand that 350mA is the rated current of the LED they’re testing. So the “worst case” 10mA that they’re using as an example of low current, would put out something like 3 lumens (assuming a forward voltage around 3v). Moonlight mode on flashlights would be far worse than that.
I’m tempted to test this hypothesis. I have a couple of Astrolux A01’s that I have hardly used at all. I could compare outputs, then leave one of them running in moonlight constantly, changing the battery every few days. But it would take so long! Likely over a year. I’m not sure I have the patience for that.
I have used a couple of other lights like that, but I have no baseline to compare them against. They don’t seem any dimmer than when they were new, but that’s strictly by memory, and an old memory. So, it’s not a reliable test example.