iCloud+ in settings says I have 701 duplicate videos (73.95GB) but it is not true

Dear Community,

We are using iCloud+ with my wife and we have just past the 200GB size. I went to check if I can consolidate data there - most data is from the Photos app (we are using Personal Libraries and one common Shared Library). In the Photos app there is no duplicate option under the Utilities section. In the Settings > Apple Account > iCloud page I see my Photos, when I click it it says I use ~120GB data for Photos in iCloud. If I click Manage storage it will show in the next page that I duplicate Photos & Videos. If I click it it shows I have 701 duplicate videos (73.95GB). In the proposed duplicate list there are videos which are clearly not duplicates. There is only one version of them, I can check it on my iPhone and in the iCloud website as well. I tested it with one non-important video and when I selected delete it deleted the only instance I had of the video. I went completely gone, no version remained neither on my iPhone nor my iCloud.

This is very scary and a horrible experience. Why do I see this and how can I repair the system to not suggest false duplications?

(Gladly I have a separate backup solution to my NAS, so I have everything on a separate location as well.)