iCloud & iCloud Photos · iCloud Photos and the Photos library
Does iCloud Photos use my iCloud storage?
Short answer: Yes. Photos and videos in iCloud Photos count against your iCloud storage plan. Optimize Mac Storage saves space on your Mac, not in iCloud — the originals are stored in iCloud either way.
Yes. Every photo and video in iCloud Photos is stored in your iCloud account and counts against your iCloud storage plan, together with iCloud Drive, device backups and other iCloud data.
Optimize Mac Storage saves space on your Mac, not in iCloud — the originals still live in iCloud either way.
To reduce iCloud usage you have to remove things from iCloud itself, such as deleting videos you don't need or turning off iCloud Photos for a device. Storage Studio frees space on your Mac and drives; it doesn't change what's stored in your iCloud account or your iCloud plan. See iCloud storage is full.