dude.....you contradicted yourself.....your own words..... go back and read them again. No need to be insulting.....Have you been living under a rock the last 10 years. Do you remember iOS 10.0 and then what difference it made when Apple switched to APFS and other things?
Every year it's like that, but please use max setting on the ignorance.
I have had every iPhone released.....and every major update slows the older models down......
It is just the way it is......