Unfortunately I cannot give access to the site.
I can guarantee that in custom fields there is no option for “Featured image”.
Hello Chiara Rendekova,
to your question:
“Did you set any particular image in those settings which might appear for your posts when sharing them instead of the image you want?”
the answer is no
I tried your solutions but it doesn’t work.
These are custom fields, I don’t have an option for highlighted image, there is only image in the article body
for example this article does not take a highlighted image https://www.farmaciaalcorso.com/it/promozioni/swisse-enterobalance-capsule/