Both Apple and Google start stripping apps out of the store once they stop shipping updates. And Apple in particular deprecates APIs like they are going out of business.
Not to mention things like the whole 32->64bit transition that dropped all previous iOS apps (and on the MacOS side of things, we've had 4x of those in the past 25 years - classic->OSX, powerpc->intel, 32->64bit, intel->M series)
Google is really the more strict of the two here. On the App Store you can get away with shipping an update from an old version of Xcode once every couple of years, while Google will boot you if you don’t increase your SDK target (which entails updating your whole toolchain and probably several dependencies too) once every year. Deprecations are pretty soft and many of the APIs deprecated well over a decade ago still technically function.
The major platform transitions are harder breaks but are pretty rare. We’re not going to another architecture shift or bit increase for a long time.
Not to mention things like the whole 32->64bit transition that dropped all previous iOS apps (and on the MacOS side of things, we've had 4x of those in the past 25 years - classic->OSX, powerpc->intel, 32->64bit, intel->M series)