This problem is fixed, but unfortunately I don’t know how 😉
The intervention I was doing was switching the PHP version from 7 to 5 and from 5 to 7 because of error 503 and excluding some for liking and sharing on social networks from Jetpack.
By the time I open the site from my phone, I go straight to the blog and normally see the pictures (I only saw text before, without the pictures of the articles).
Thanks!