13Mini+Lockdown mode user reporting here: I did a battery upgrade alongside the iOS 26 upgrade, and regretted switching to iOS26. It slowed down things wayy to much, the keyboard often lagged by dozens of keystrokes, and the camera app stopped working with 26.1.
I gave up yesterday, and disabled lockdown mode (and upgraded to 26.2). Seems fine now, but liquid glass is still a usability nightmare.
Running iOS 17.6.1 on my iPhone 13 mini right now. I've got a backup iPhone 13 mini new in the box with the factory OS still installed (just in case).
I'm hoping my devices can hold out longer than Apple can remain irrational.