Almost feel sorry for them?
I have a litany of Apple devices and the problems started in Sept. with the new launch. It’s a software crime.
Two Xmas purchases didn’t happen from me.
I have three devices. I have an iPad Mini 2 and a iPad Pro. (I think Pro is the model).
My new iPhone X works great. There have been no issues with it or my iPads.
You may have a valid issue with Apple. You couldn’t prove it by me. Even if we see numerous reports on the internet, there must be a whole lot of people out there like me too.
It’s hard to gauge these things, not being too dismissive or too inclined to assume some dastardly plot.
It could not have been that.
The updates in question with the Battery Power Management update are iOS 10.2.1 release January 23, 2017 which installed that function for just the iPhone 5s, 6, 6 plus, 6s, 6s plus, and then iOS 11.2 released December 4. 2017 which installed that Battery power management update for iPhone 7, 7plus, 8, 8 plus, and X.
So September's release had nothing to do with the Battery Power Management unless you waited that long to install the iOS 10.2.1 update.
There were some slow-down issues with the iOS 11 release that had nothing to do with that but those were handled by point updates that fixed minor issues. Also if you did not do a complete COLD, HARD RESTART of your devices after the September update, which resets the registers, you could still have some slow-downs.