I remember this sort of madness constantly. At that time, the Unity to iOS build process involved exporting projects to Xcode including C OpenGL code, which I would sometimes have to fix as it their compatibility would drift.

Even currently I don’t allow Visual Studio Mac to update after I learned the hard way that the new version needs new Xcode, which needs new macOS which isn’t even available on my computer.

(I only recovered a working setup using Time Machine.)