Mobile data issue
My iphone show An update is required to use mobile data on this iphone
See these Apple articles below:
If you see No Service, Searching, or SOS on your iPhone or iPad
If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support
Manually update your carrier settings on your iPhone or iPad
Manually update your carrier settings on your iPhone or iPad - Apple Support
Update your network provider settings manually on your iPhone or iPad
Update your network provider settings manually on your iPhone or iPad – Apple Support (UK)
If you see a Cellular, Ultra Wideband, or Apple Pay Issue message after an iOS update or restart