This is more of a <> than a question…
This evening I logged out of iCloud on my iMac, rebooted, then logged back in. (There was an issue with my iCloud and the forums suggested logging out/in.)
Now - Photos app is re-uploading all 30k+ photos and videos to iCloud. I purposely have my iMac/Mojave set to keep a local copy of our photos.
That is all…