Why do I have to upgrade to iCloud when do not want as I take regular backups?

The article below has steps to check your iCloud Storage. If all looks good there, consider the emails as spam. I have seen dozens of similar emails in the past months, usually with threats of deleting my photos, etc. …… all are scams. If you are indeed using all your iCloud storage, take steps to lower that usage.

Check your iCloud storage on any device - Apple Support (CA)

And why do you believe you need to upgrade your iCloud?