So here is the scoop — Steinberg has been trying for years to get developers to stop using VST2 and switch to VST3.
So they basically banned the use of VST2 for new developers, meaning that if you already had a license to use the older version, you could continue to use it but if you are a new developer, you are no longer allowed to use the older VST2 format.
The thing is, VST2 has been around a lot longer than VST3 and so have just tended to be more reliable than the newer format which does a lot of things differently (and breaks some things, for example VST3 stopped supporting Program Change messages by default).
So I will only use VST3 if a VST2 version is no longer available. That said, since I rarely update my touring environment (I’m still running a machine with macOS 10.14), I rarely need to use VST3 versions