Moved library for internal to external - uploading all again?

[MrMister111]

I copied my Photo library from internal to an external drive as getting too big. I then double clicked the new library on the external drive, and set as use this as system library. All my library was full downloaded, not optimised. I followed this https://support.apple.com/en-gb/HT201517 I also use iCloud photo library

However on the bottom of the Photos menu where it shows total photos and videos, it says its uploading all my library, as in 32000+ items! why?

I use iCloud library, all my pics and videos are already in iCloud, I've ticked use iCloud library, all I've done is move the actual library from one place to another (internal to external), why do I have to upload all again?

 

[NoBoMac]

Simple copy vs Time Machine backup (per other thread you have)?

If simple copy, Photos and iCloud Photos allow for only one master. So, can see that trying to resolve the iCloud copies with " new"master.

Not an iCloud photo user, so, hopefully some one that has done this can enlighten, if just going through busy work to "match". Me personally, I copy my library, external as well, to other external drives I have lying around (an OCD 3-2-1 backup type thing, so no need to iCloud).