I'm not a lawyer, but I think it's the same situation as admin boundaries. What is the source of the boundary of Austria? And it's counties? They are coming from similar laws.

If you want to revert it, please do it, but remove all already mapped data, not just from this changeset, here is an overpass of all the nuts1 regions: https://overpass-turbo.eu/s/1IqS

Around 2000 more regions have different level of nuts code added, please remove that data as well: https://taginfo.openstreetmap.org/search?q=ref%3Anuts#keys

And please update the wiki: https://wiki.openstreetmap.org/wiki/NUTS_and_LAU