My iCloud isn’t backing up when I attempt to

Hello, my iCloud storage is 626.3MB used out of the 5GB storage limit. Every time I try to back up my iCloud it keeps giving me this error message: “This iPhone cannot be backed up because there is not enough iCloud storage available.” I even checked my iPhone storage and it’s 53GB out of 256GB used. And that’s a new Apple ID that I made around a month or two months ago. Because with my other Apple ID that was the exact issue. Any help will be appreciated. Thanks