Invalid Mex file of both earlier and latest Dynare on macOS

You are misunderstanding what I said. I referred to 5.1. Each Dynare package for Mac was designed to work with a macOS version running at that time. For 5.1 it is Monterey.
Of course 4.4.3. was not designed to work with Monterey. That’s why it typically will not work with newer macOS version unless you build it from source.