A powerful upgrade is on the cards for the entry-level iPad, according to Evan Blass. The current 10.2-inch tablet has the A10 Fusion chipset from 2016's iPhone 7 series, but the 2020 edition could see a jump to the A12X Bionic. Excess stock may be the reason for bringing the former-iPad Pro chipset to the 8th generation iPad, which should be compatible with the Apple Pencil and Smart Keyboard too.
https://www.notebookcheck.net/Apple-may-be-planning-a-powerful-upgrade-for-the-entry-level-iPad.494230.0.html
Lock some cores or downclock clock them, voila, no threat to Pro/Air models.
I find it hard to believe they have too much A12X stock, its use was limited from the beginning intended for the iPP line, and big chips are clearly more expensive, why order that much? That said, whatever excess they have from the scale of the iPP line will be miniscule adapted for the entry line's volume, so unlikely either way.