Blurred images

[PaoloPev]

Good morning,

I don't know why, when I open the product pages, I see blurred images.
If I select a variation, all come back right.

Can someone explain me the problem and how to resolve it?

Link for an example: https://www.martinigioielli.com/fido/68-2521-pendente-zampa-25.html

I've tried to purge the cache but nothing... my settings:

PS 1.7.6.0
Compiling the template FORCE
Cache YES
Multi-front Optimizations NO
Cache type FILE SYSTEM
Purge Cache EVERY UPDATE
 

Thank you in advance 😊