I believe it’s like 20MB a photo compared to 2MB a photo so takes up about 10 times the space but I have a 512GB iPhone, 2TB of iCloud storage, and 100TB on my NAS at home so I’m not hurting for storage and it doesn’t affect me as I offload all my photos to my NAS so if I ever run out of device or iCloud storage I can just remove some as they are all on my NAS.