I am asking because older versions of UUIDs (GUIDs) are probably in violation of European privacy law.
In addition to GUID privacy considerations, I've heard there is also a problem of "green" GUIDs.
Since the number of GUIDs is a limited resource, you could consider recycling them.
Try sending an email to European Commission on Green Energy and other green stuff, containing the list of GUIDs which are not in use anymore

More seriously, as far as I know, it is not that "version 4" is any newer or better than "version 3", it is just how the GUIDs are generated (algorithm marker). Actually, "4" is "pure random number" and "3" is not.
I am also not aware of any privacy regulations that apply to GUIDs (as soon as they are actually GUIDs)? But maybe I am missing something?