I’m not sure how I would measure this, but it doesn’t match my experience.

I have a Gen 3 WP PVS-14 that I use quite a bit. There is sufficient IR light outdoors pretty much all the time to see quite clearly with it, even with a new moon. The only time it’s difficult to use passively is if it’s extremely overcast. Even then, the tiny, weak IR LED on the device itself is enough to reach out to 50 yards or so.

Think about standing in front of a bright infrared source, like a space heater. You can't see the infrared, but you can feel it on your skin.

If you pay attention you can pick up more subtle infrared sources, for instance certain kind of light bulbs. But in general it feels pretty "dark."

this speaks more to the sensitivity of gen 3 white phosphorous than the abundance of infrared

as you say, it only takes a weak LED to work as a flood light