Clarify Photos Uploaded From Finder Will Be Removed

Abrasrose wrote:

I’m trying to clarify what happens when I turn on sync photos to iCloud.

1 - The photos on the backups via Finder will not move over to another device such as an iPhone or iPad.

2 - Photos in those backups will remain on the computer they were backed up on through Finder.

3 - The photos that were backed up via finder can still be viewed in Photos on the computer.

4 - No photos are deleted from the computer and become irretrievable.

5 - You cannot restore any photos you have lost from a backup on an external drive.

No idea what you mean by backups via Finder. Do you mean backing up your iDevice to your computer instead of to iCloud? Any backup of a device on your system is unaffected. When you turn on iCloud Photos, photos on your device are synced to iCloud and then to any other device on which you have enabled iCloud Photos. That's it. If you edit, delete, create, etc. it is reflected in iCloud and across all devices.