Google’s John Mueller reminds webmasters on Twitter that when it comes to images, Google is slow at updating the URLs and changes.
That being said, John Mueller said make sure to use image URLs you can control, even if you use a CDN (content delivery network). If your URLs for your images are constantly changing, it can cause serious issues for Google with image search. He said keep the URLs the same and control them.
John wrote “CDN URLs is fine, but I’d try to avoid moving image URLs too much, so I’d tend towards using your own domain/subdomain (via CDN).”

CDN URLs is fine, but I’d try to avoid moving image URLs too much, so I’d tend towards using your own domain/subdomain (via CDN).
— John ☆.o(≧▽≦)o.☆ (@JohnMu) October 17, 2017
Here was the original question:

Is it fine to use images from CDN provider URLs or images should have our domain or sub-domain in it?@JohnMu @dannysullivan @pedrodias
— Sandeep Malviya (@sandeepmalviy) October 17, 2017
Forum discussion at Twitter.