"CC0 has not been approved by the Open Source Initiative and does not license or otherwise affect any patent rights you may have. You may want to consider using an approved OSI license that does so instead of CC0, such as GPL 3.0 or Apache 2.0."

https://wiki.creativecommons.org/wiki/CC0_FAQ

CC0 is great but it does not go far enough for software. Patent and trademark rights are complex and it caused CC0 to be withdrawn from OSI consideration.

https://lists.opensource.org/pipermail/license-review_lists....

I do not know why it has to be so legally complicated to say TAKE MY WORK IT IS FREE FOR ALL.

IMO ISC is the current best OSI approved option for ensuring technical work can be used as broadly as possible and is what I use for recent work.

https://www.tldrlegal.com/license/isc-license

Show me something OSI compatible less restrictive than ISC and I will use that.