Syncing iCloud Photos without deleting old photos from iCloud

My iphone 13pro max 128gb and recently i ran out of space. So i bought iCloud 2TB and synced all the photos/videos there and deleted them from my device. I have now stopped syncing otherwise the my iphone photo gallery which is now only 50 photos will be synced to icloud and i will lose all old photos videos. Now, my question is, since stopping the sync, how can i upload the new photos and videos to iCloud without deleting the previously stored 200gb sth photos and videos.

the whole icloud setup is very confusing to me so please help. I cannot afford to lose all the photos of important life events!