I'm guessing that the people who have this cracked keep it a secret so only their inner group has the method which lets them leak all of the new content and Google has no idea which key or process has been cracked.
> In addition to this request, we have filed a separate Sensitive Data takedown request of this file: /widevine-l3-decryptor as it contains the secret Widevine RSA private key, which was extracted from the Widevine CDM and can be used in other circumvention technologies.
> In addition to this request, we have filed a separate Sensitive Data takedown request of this file: /widevine-l3-decryptor as it contains the secret Widevine RSA private key, which was extracted from the Widevine CDM and can be used in other circumvention technologies.