This is actually a necessary feature for a touchscreen keyboard to feel usable, and it's been in iOS since day one. The problem is that it has gotten not only much worse over time at predicting which tap zones to enlarge, but it also feels more aggressive. For example, tapping the shift button on the iOS keyboard enlarges the Enter/Return key's touch area so much that I am unable to immediately tap the microphone icon to turn off dictation. If I've tapped shift, I need to then wait a second for the predictively-enlarged tap zone to shrink before I can turn off dictation.