My Photo Stream is shutting down on July 26, 2023. Only the copies of your photos stored in the My Photo Stream folder in iCloud will be deleted. Photos in your Photos libraries on your devices are safe. Learn more about this transition and how to keep your photos up to date across all your devices and safely stored in iCloud by reading this support article —> Information about the My Photo Stream shutdown - Apple Support
"My Photo Stream" dates from 2011 and is an old precursor to iCloud Photos which replaced it in 2015*. Many people have never used it or have since transitioned to iCloud Photos. If you don't see a My Photo Stream folder/album in iCloud Photos then you don't use it and don't have to do anything.
1) Go to: Settings
2) Choose Your Name / AppleID
3) Go to iCloud
4) Go to Photos
5) See if you have My Photo Stream. If you do, read the support article about what to do.