I am in an area where 5G UW (AT&T has it as 5G+) has some coverage. Usually in an area with more than 2-3 bars. I do have cellular enable for photo/backup. I have 5G Auto turned on. I will try and see if turning cellular enabled turned off will help in the next few days. I am having issues photo icloud not syncing since I’ve gotten this new iPhone 15 Pro. Very frustrated with this phone and iOS 17 in general.It could be something to explore. Are you in area where 5G UW available? Do you have low signal bars? Do you have iCloud photo/backup enabled on cellular? Do you have it set to 5G Auto or 5G On for Voice & Data or Allow More Data on 5G for Data Mode?