Apple have already paid numerous fines for planned obsolescence - it’s not up for debate whether they do it or not, but the fines are a drop in the ocean compared to the additional revenue it generates.
Everyone has a smartphone, and they’re a mature product so there is less incentive to buy ‘the new model’, but Apple need to increase profits year on year for shareholders, so they’ve got to force users to keep buying new phones somehow, otherwise profits will decline.
They’re clever about how they do if of course. It seems to UI issues are built into the software so you can’t escape them by not upgrading the iOS, and many of the issues seem to be triggered on a random selection of devices. If everyone encountered exactly the same ‘problems’ it would be obvious.
These ‘issues’ will likely become more obvious and more widespread as the need to increase sales of new models increases.