Missing some photos and videos after backing up my iPhone.

Hi azzaya,

Welcome to the Apple Community.

Apple support have an article online (link below) that may help:

If you're missing photos or videos in the Photos app - Apple Support

If you are using iCloud:

Get help with iCloud Photos - Apple Support

If you still need help:

There is a "Get Support" link (at the very bottom), on the Photos Support website (link below)

Photos - Official Apple Support

All the best :-)

PS: If needed:

How to use iCloud to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch:

Transfer your personal data and purchased content to your new device using your previous device's iCloud backup:

Use iCloud to transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support