Shared Album limits
Shared Albums don't count against your iCloud Storage, but there are limits to the number of photos, albums, and invites that you can share.
Shared Albums limits
These are the Shared Albums hourly and daily limits:
Maximum number of photos and videos from a single contributor across all shared albums, per hour: 1000
Maximum number of photos and videos from a single contributor across all shared albums, per day: 10,000
Some additional limits for shared albums:
Maximum shared albums an owner can share: 200
Maximum shared albums a user can subscribe to: 200
Maximum subscribers per shared album: 100 (the number of subscribers on each shared album)
Maximum combined number of photos and videos from all contributors in any one shared album: 5000
Maximum number of comments per photo or video in a shared album: 200 (a comment can be either a like or a text entry)
Maximum characters per comment: 1024
Maximum number of invites a shared album owner may send per day: 200
Supported file types for Shared Albums
Shared Albums upload a copy of your data. Downloaded content may not contain the same information as the original.
Image formats: HEIF, JPEG, RAW*, PNG, GIF, TIFF
Video file types and formats: HEVC, MP4, QuickTime, H.264, MPEG-4
Shared Albums also support special formats that you capture with your iPhone, like slo-mo, time-lapse, Live Photos, and Memory videos. When shared, photos are reduced to 2048 pixels on the long edge, except panoramic photos, which can be up to 5400 pixels wide. You can share GIFs that are 100MB or smaller. Shared Albums do not support spatial photo or video.
Videos can be up to fifteen minutes in length and are delivered at up to 720p resolution.
Due to storage limitations, your Apple TV might display only your most recent photos.
*You can't upload HEIF images, HEVC videos, or RAW photos to Shared Albums on your Windows PC.
Sharing Suggestions limits
Sharing Suggestions are limited to 5000 items with a maximum share size of 1GB.