Optimize photos on iPhone without affecting Mac storage

A lot of my files on my Mac are in iCloud only, and I don't know how that happened. Could my changing my iCloud to Optimize on my iPhone have affected my Mac as well?

On the Mac, I have plenty of storage space. I want EVERYTHING on the Mac, and it's nice to also have it backed up in iCloud but not necessary.

Can someone advise?

[Re-Titled by Moderator]