since you have selected iCloud Photos, doing that automatically removes the (essentially redundant) feature of My Photo Stream.
depending on how much GB of photos you have, storing them in iCloud may cost you monthly money for iCloud storage.
if you don't want to pay for storage on iCloud, then you would need to de-select iCloud Photos and then select My Photo Stream in order for photos to "sync".
My Photo Stream does something similar to iCloud Photos, but in practical usage ways its very different.
Although it does sync photos' basic info across devices, you will need to manually import those photos into Photos if you want to ensure they are secure within yr Photos app library on yr other devices.
it does not "sync" continuosly therefore all photos; it gives you an opportunity for you to manually get these photos into yr devices' photo library.
after having selected iCloud Photos as you have already done then de-selecting it now may mean you need to re-download photos to yr mac within 30 days or lose your photos entirely.
so be sure to pay heed to whatever message/info you receive when de-selecting it iCloud Photos.
Bumping this thread because I spent 30 minutes pulling my hair out on this. Someone correct me if I'm wrong, but it used to be the case that you could have *both* "iCloud Photos" *and* "My Photo Stream" enabled, right? I seem to recall articles even having been written that suggested that it wasn't a bad idea to use both.
On my wife's 2018/2019 (I forget which) MacBook Air that I looked at earlier today, I'm fairly positive that she had both options available to her inside of the Photos app's Preferences/iCloud settings, whereas on my 2019 MacBook Pro 16, if I select "iCloud Photos", then the option for "My Photo Stream" disappears. If I uncheck "iCloud Photos", then the "My Photo Stream" option reappears. If that's the intended behavior now, then OK, but why are they using check boxes instead of radio buttons for these options, if they're now mutually-exclusive?
I just upped my iCloud storage to 2TB, so I guess I should just enable iCloud Photos, right? If so, I'm pretty sure that I also want to check off "Optimize Mac Storage" instead of "Download Originals to this Mac" as I don't want my MacBook's SSD to get filled with my entire photo library. Does this sound right?
Or are there still use cases where I might want to instead enable "My Photo Stream" on my MacBook?
Assuming that I'm OK using "iCloud Photos" in conjunction with "Optimize Mac Storage" then how would I go about uploading old photos I might have on a hard drive to iCloud, such that I don't have to keep them stored permanently on my MacBook?