Comment by krackers
The single biggest change in both ios and android is the swiping everywhere, and lack of button depth. Now it's impossible to navigate, and impossible to know what's a button or not. The only way is to just try tapping and swiping everything.
I remember a bug/feature report for some Android ROM complaining that switching the 3-button navigation layout to have the back button on the right side, and someone mentioned that they probably wouldn't do that, since button navigation was going to be deprecated in favour of gestures anyway, so no point in putting in the effort.
The comments following that one weren't very kind. And I agree with them. I'd hate for gestures to be the only option, and find the 3-button layout option to be the saving grace saving me from dreading to use my phone. I can't imagine that option disappearing, precisely because Grandmas and the like need that option to use their phones, but the fact that there are people out there who see that option as deprecated, and not even as an accessibility option at best, scares me. That thought is the start of process that eventually ends with some critical functionality being removed and never coming back, breaking a category of device for a large group of people, in a similar way to how the X11 to Wayland migration has broken several accessibility features on Linux.