Why are you changing our iCloud Photos when we pay monthly fees for storage backup?
How do I save my iCloud Photos to my iMAC?
iMac 27″, macOS 11.7
If you are talking about what's in this article: Information about the My Photo Stream shutdown - Apple Support
that isn't iCloud Photos. It is an earlier photo storage feature that Apple is now replacing 100% with iCloud Photos. If you are already using iCloud Photos then nothing will change for you. If you aren't, read the article for what to do.