Safari on iOS devices is loading corrupted images - Wordpress site

While supporting our WordPress Clients, I've faced such an issue dozens of times There are two general reasons for such a behavior:

1. You're using some CDN (Content Delivery Network) which you didn't mention in your question, and different CDN servers output different website cache version. If you're using CDN, try to purge your local plugin's cache, disable your local plugin and purge your CDN cache.
2. Sometimes images thumbnails may be corrupted, while they still exist. Try installing "Force Regenerate Thumbnails" plugin and regenerate all the thumbnails.

Though two above reasons are the most common, the issue itself may be connected with something else as well, for example, with some particular plugin. For this case it might be a good idea to temporarily deactivate your plugins one after another and see if the issue is resolved.

In case any of these won't help, it will require some debug work, so it could be a good idea to hire some WordPress developer for about an hour to fix this.

Good Luck!

If you have access to a mac + safari you can try remote debugging your iOS device. If you do this you could open the developer toolbar for the device so you can see if the information is actually being loaded. ie. if the messed up image is 300k on the desktop site, but the iOS device is loading a 30k image, you would know you're losing data somewhere.

I've not seen this specific issue, but I've had similar issues pop up due to bad CDN links, caching plugins, and lazy loading of images.

Another note to look for would be if your theme/template/plugins are using src sets. It could be possible that your normal version of the image is fine, but the images in the srcset for mobile are all messed up.

As noted above, completely disable w3 cache to troubleshoot that it's not the issue. Then take a look at the plugins.