How to stop syncing photos between all devices?

If you don't want your photos on your Mac to not sync with the other devices then don't turn iCloud on for the Mac. Make sure it's not on. Click on your photos app, and then click on "photos" at the top beside the Apple logo, click on settings, and make sure iCloud is not ticked there. If it is, untick it.

This article describes how iCloud Photos works. Set up and use iCloud Photos - Apple Support

iCloud Photos will sync all devices that have the same Apple ID. You can shut off syncing from any device, but you won't be able to have photos uploaded to iCloud and not show up on a device that has syncing turned on.

The intention of iCloud Photos is so all devices that participate will have the exact same photos, it is not used for photo storage where you can upload from individual devices to store in a central location without having them on the others.