how do i stop my iphone photos from syncing to my ipad??

11 iPad Settings You Need To Turn Off Now [iPadOS 15]

On your iPhone, iPad, or iPod touch:If you’re using iOS 10.3 or later, go to Settings > [your name] > iCloud > Photos, then turn off iCloud Photo Library.If you’re using iOS 10.2 or earlier, go to Settings > iCloud > Photos and turn off iCloud Photo Library.Oct 1, 2017

Synology Integration with macOS and iOS — Synology Webinar