But in the recommended CC0 licence it says something different. "If you want to release your non-software work to the public domain, we recommend you use CC0.

But in the recommended CC0 licence it says something different. "If you want to release your non-software work to the public domain, we recommend you use CC0. For works of software it is not recommended, as CC0 has a term expressly stating it does not grant you any patent licenses. Because of this lack of patent grant, we encourage you to be careful about using software under this license; you should first consider whether the licensor might want to sue you for patent infringement. If the developer is refusing users patent licenses, the program is in effect a trap for users and users should avoid the program." The issue is apparently patent sueing. Sigh.