Yes, Apple doesn’t care about backwards compatability, so you might have to update your application so that it runs on the latest macOS version, but there’s no way around it.
You either have a gazillion competing frontend APIs to maintain compatability with shit that was written for Windows 3.1, or you don’t care about any of that and end up with almost entirely consistent visual styles across the entire OS.
They killed the butterfly keyboard in 2019 (almost 4 years after it was introduced), and they killed the touch bar last year.
Yes, it took them some time, but they sorted these things out.
Or the ever more locked down environment, or the iOS style dumbed down apps they prefer now..
I think it was pretty much downhill after leopard :(