How do I make certain no one steals my credit card information?
if I want to use my credit card to pay for more ICloud storage, how do I know it is safe against anyone?
iPhone 11, iOS 16
As much as you trust any retailer with your credit card information. In 18 years of having been on this forum I can't remember anyone actually saying their credit card number was stolen because of lax security on Apple's part. More likely is an account owner not taking adequate steps to protect the security of their information.
Personal Safety User Guide - Apple Support
> open the Table of Contents
A document with general information about security and your Apple ID --> Security and your Apple ID - Apple Support