A8X iPad Air 2 (2014) and A8 iPad mini 4 (2015) are different generations devices based on the same chip family. But both were dropped at the same time with iPadOS 16.
iPadOS 16/17 features are polyfurcated compared to iOS 16/17. For example, all devices that run iOS 16 support Visual Look Up. But only A12 or newer iPadOS 16 devices support that feature. This is even worse with iPadOS 17. Given A10 iPads already received leniency, I don't think Apple will do it again this year.
View attachment 2353687
Sometimes RAM matters. Other times it's processor. I've not seen a situation where Apple drops support solely based on launch date or generational attributes.