Some models of the M4 iPad had 3P + 6E = 9 cores as well, so it's certainly not unusual. Like another commenter said, the "why" can be binning for chips which c

Some models of the M4 iPad had 3P + 6E = 9 cores as well, so it's certainly not unusual. Like another commenter said, the "why" can be binning for chips which come out with a broken P core.