Apple tends to expect a lot from its developers. Changing processor architectures is a big one. Unlike other platforms, Apple cuts support and moves on. If an app is abandoned, it starts to show sooner on Apple platforms than anywhere else.

If it’s something that will become critical to a user’s workflow, that can be a big problem. Why invest in an app without a future?

I think the reasonable fear is that the product no longer works. Maybe Apple changed a required API in 2021 and poster would be purchasing a lemon.