I can’t find what’s causing it. Cornerstone. Image element (not classic image).
In preview it’s clear (see the screenshot):
On live site it’s some 20% worse.
I’ve tried uploading 5 MB original PNG file and edited 200 KB JPG. The same result. On preview it’s pretty, on the live site - crappy. Changing file name every time, so it’s the new image I’m seeing, not catched one.
The only setting I’m changing is Box shadow. The rest I haven’t touched.