Phone keeps saying it’s storage is full
Try to free up iPhone device storage see this Apple articles below:
If you need more space for an update on your iPhone, iPad, or iPod touch
If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support
How to check the storage on your iPhone, iPad and iPod touch
How to check the storage on your iPhone, iPad and iPod touch – Apple Support (UK)
Clear Other storage on your iPhone or iPad
Clear Other storage on your iPhone or iPad - Apple Support
but I have a TON of space in the cloud.
See the following Apple articles:
What's the difference between device storage and iCloud storage?
What's the difference between device storage and iCloud storage? - Apple Support
How to use iCloud on iPhone
How to use iCloud on iPhone – Apple Support (UK)
Get help with iCloud Photos
Get help with iCloud Photos - Apple Support
Set up and use iCloud Photos
Set up and use iCloud Photos - Apple Support (IN)
Check your iCloud storage online or on any device
Check your iCloud storage online or on any device – Apple Support (UK)