I thought they binned CPUs for things like AppleTV and lower cost iPads?

Yeah, most of their chips have two or more bins with different core configs, and the lower bins probably use salvaged dies.

For example the regular M4 can have 4 P-cores / 6 E-cores / 10 GPU cores, or 3/6/10 cores, or 4/4/8 cores, depending on the device.

They even do it on the smaller A-series chips - the A15 could be 2/4/5, 2/4/4, or 2/3/5.