When Peter and I pm'ed, I forgot the standard tail amps on these things is 2.3-2.5A amps now. Used to be over 5A when they did a true 1,300 lumens, like the Manker U21 did in my review: https://budgetlightforum.com/t/-/40242.
So the new 2.4A version does about 1,000 lumens. With Peter's doing ~650 lumens, I'd suspect the LED, LED mount, and/or optics, but could still be a driver problem I suppose.
He's right though - they downgraded the light but never downgraded the specs, but if the measurements are good, his is performing below par of even the downgraded model, but the amps drawn from the cell is not producing the same output.