A CDN change affects more than the main image you see. Old image URLs can remain in articles, feeds, CSS and responsive source lists. A new image on the product page does not prove that the migration is complete.
Trace an entire image family
Fictional example: the large product image uses the new CDN. On small displays, the browser still selects an old address from srcset, and that file has been removed. Only some viewport sizes expose the failure.
For one image family, record the original file and generated sizes. Use the network panel to see which URL the browser actually requests. Include background images and public feed entries where the project uses them.
Map old public addresses to their new counterparts. Reusing a filename must not accidentally send an old image request to a different subject.
Width, format and quality parameters may work differently with the new provider. Check the resulting format, dimensions and visible image rather than transferring parameters unchanged.
Update the project’s source references and assess redirects for old addresses you control. Google’s image guidance emphasises accessible image URLs; it does not promise immediate reappearance in image search.
A documented sample covering mobile and desktop requests is a more useful handover than a blanket statement that the new CDN is active.
Related check: Prioritise a redirect mapping.
For defined changes to image sources and responsive output, you can enquire about Frontend optimisation.