Large Photos Container

Yes, it is expected, if you are sharing many photos and videos in shared albums.

The folder you are showing is the folder in your user library, where iCloud is storing the local copies of all photos and videos you are sharing in shared albums or downloading from shared albums, where you accepted an invitation to participate.

To free this storage, export all photos from shared albums from your Photos Library to an external drive and then delete them from the shared albums. The photos in the albums you shared will be removed from iCloud, when you do this.