Issues with iCloud photos

Recently my phone storage was getting too full so I synced it with iCloud and chose optimise storage. Now the ~180gb in photos has become 18GB but the iCloud storage on iCloud is 199GB of photos.

How can I lower this? Theres more in iCloud than there ever was in my gallery which seems insane.

And it hasn't even finished syncing yet. I have ~24k photos on my phone and only ~20k have synced to my iCloud.

I've also got a lot of pointless photos I want to delete, should I delete these on iCloud dot com or should I delete them on my photos app? I'm not sure how the sync features works when there's not enough storage and I'm still actively deleting photos