If "_key2" is an public key embedded within Windows, then presumably there exists one or more holders of the private key somewhere - what exactly are they able

If "_key2" is an public key embedded within Windows, then presumably there exists one or more holders of the private key somewhere - what exactly are they able to do with this key? I've seen a lot of concern about "_key2" and "_NSAKEY" being expressed over the years, but scant technical detail.