Why is my backup amount so low when it should include 200 gb of photos?

"Why is my backup amount so low when it should include 200 gb of photos?: [...]See, it shows 174.3 GB at that moment. When it finally got completed, my backup shows 3.11 gb. If you look, it shows that the photo library included in it is 201 gb. How does that make sense? It can’t be included if it’s only 3.11 gb. Could someone help me?"

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Thank you for the screenshot.

Enable Photos in iCloud:

1. Go to: Settings
2. Tap: Your Name (Top Item)
3. Tap: iCloud
4. Tap: Photos
5. Enable: iCloud Photos

Transferring Photos from an iPhone to a Computer:

Speeding this Up: You can transfer these from your iPhone to your computer. Once on your computer, upload the by enabling Photos in iCloud Settings. Go Here: Transfer Photos and Videos from your iPhone, iPad, or iPod touch to your Mac or PC - Apple Support

If the photos were all taken on the phone and never sync'd to and from your computer then they should backup.

Any other scenario, including having iCloud Photos turned on, they will not back up.

As a test, view an old photo and see if the trash can appears. If it doesn't then it may have been sync'd from a computer.

I would just add that 200GB of photos will take several days to transfer to iCloud, do not change your mind halfway thru like you already have done before.

You will need good unlimited data plan, preferably on wifi

If you start and stop it, it may be unpredictable.

Cannot answer that without knowing the source of the photos. If they were sync'd from your computer then you backup the computer.