icloud photo Synced is not showing I have iPhone 8 with iOS 13.2 and iTunes version Version 12.10.2.3
but the option to add photos(photo Synced) in iPhone is not showing
The message is self explanatory. iCloud for photos syncing is "on". You should access the photos using iCloud for Windows and iPhone's Photos.app. 


https://support.apple.com/en-us/HT204283
https://www.microsoft.com/en-us/p/icloud/9pktq5699m62?activetab=pivot:overviewtab


See these for more info. 


https://support.apple.com/en-in/HT205323
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