Hi Cmwx,
For help with iCloud Photos check to see if the 'Optimize iPhone Storage' feature is turned on. The steps below found in the article here can assist: Use iCloud Photos on iPhone
"Save space on your iPhone
iCloud Photos can help you make the most of the storage space on your iPhone. When Optimize iPhone Storage is turned on, all your full‑resolution photos and videos are stored in iCloud in their original formats, with storage-saving versions kept on your iPhone as space is needed.
Optimize iPhone Storage is turned on by default. To turn it off, go to Settings > [your name] > iCloud > Photos, then tap Optimize iPhone Storage."
You can also find helpful information here: Get help with iCloud Photos
Cheers.