If you need this, and you’re using ScreamingFrog for this, you know how to use it 🙂 No explanation, no how-to, here’s the regex to use in your custom extraction in ScreamingFrog.
<\s*img(?![^>]*loading)[^>]*src\s*=\s*["']([^"']+)["'][^>]*>
Code-Sprache: JavaScript (javascript)
Note: This only works with “simple” HTML <img> tags, not srcsets. Sorry. This was enough to get the job done for me.