What type of 18650 terminal is this?
The end is a double-sided PCB which contains the protection circuitry on the other side.
Typically this would protect against some combination of over-charge, over-discharge and over-current.
Here is a typical circuit from a Chinese source:

This is in contrast to unprotected 18650 cells as one might 'harvest' from a laptop battery pack, which rely on circuitry outside the cells for protection.
So your PCB is designed with the terminals on one end, which is not that big a deal if you pick the right end, to make the product more convenient (and lock you into one supplier).