Hi Fred,

It appears that you template adds CSS transition on <a> tags.
The <a> tag may have been in transition while image size calculation takes place causing incorrect image width/height.

While I cannot accurately determine if this is the case due to aggressive caching on your server, here is the CSS to disable transition on <a> tags within EasySocial photos.

body div#fd.es .es-photo > a {

    -webkit-transition: none !important;

    transition: none !important;

}

I have modified the "rt_corvus-custom.css" file on your site by removing the initial code provided by Mark and added the one above.
You will need to refresh your server's cache (Siteground/Cloudflare?) for it to take effect.

If it still doesn't work, please provide us temporary access to Siteground/Cloudflare so we can perform a proper test.