Apple may be using chip binning for the iPhone 16e's A18 chip.
While chip binning can be used to repurpose a damaged chip and minimize waste, it can also be used to purposefully damage a chip.
However, while it is stated as having an A18 chip powering things, it's not the same A18 chip as used by its stablemate, the iPhone 16.
Here's why the act of chip binning helps Apple while also creating variants of the same chip for different products.
Doing so effectively means it's a chip that would otherwise meet all of the specifications to be used in the iPhone 16e, but not the iPhone 16.
