It appears that you have entered the iCloud sync morass, compounded by signing out from, then back in to iCloud **. This is in addition to whatever issues you might have with your iCloud storage level and your internet bandwidth.
** Signing out then signing in to iCloud from a device in which photos are stored in full resolution results in the following: the iCloud service will check every single image to see if it has been synced to iCloud. This can be very slow with large photo libraries, and is much slower than simply downloading your iCloud Photos anew to an empty system library on your device. Even worse, during this image-by-image check process no new photos come down to the Mac.
I suspect that you may have encountered this situation. For more information and a blog post describing a clever work-around, see this previous MPU Forum post: https://talk.macpowerusers.com/t/tab-groups-in-safari-on-mac-not-showing-up-in-safari-iphone-ipad/25913/3