If you look carefully using HKJ's comparator, the curve shape of the “Aspire” cells (Aspire, KeepPower, UltraFire, Vapcell) is was different. I can't say if this is due to a reduction in manufacturing costs by the same OEM, or a different OEM product altogether.

The BestFire IMR18350 was the first high discharge 1000+mAh 18350 cell reviewed by Henrik to show such (different) discharge curve shape.

It also looks like a progressive regression if you follow the reviews by date: Aspire 1st; then KeepPower, Vapcell and UltraFire (BMS protected); at last BestFire and the newer Vapcell.