What can interfere with the display of thumbnails and post previews in the wordpress blog grid?

Question

caching

My wordpress blog is rostisila.com. Something prevents the correct display of post thumbnails and post previews in the grid (on the main page and in categories), as well as in posts, in the block of similar articles under posts.
The site communicates with the server through cloudflare.com. Installed W3 Total Cache. Perhaps the reason is that yesterday I tried to make cloudflare and W3 Total Cache friends based on the guide described here https://www.besthostnews.com/guide-to-w3-total-cac... There is a suspicion that the cause of the problem is cloudflare and/or W3 Total Cache settings.
What else could be the problem?