Basically keeping the link thumbnail saved on some relays like Damus already does. With Primal, all thumbnails from nostr:npub1qfv2tudq6uawsutmzal5x8me5y26692xxfvf587wg79tl6l9q4msp5uyv9 are not shown because everytime Primal calls back to the website server to retrieve the image and is flagged as a bot.

Basically, Primal hotlinks for every URL thumbnail. If a website, like blockdyor.com, has the hotlink protection, the image won’t be shown. https://developers.cloudflare.com/support/more-dashboard-apps/cloudflare-scrape-shield/understanding-cloudflare-hotlink-protection/#:~:text=Hotlink%20Protection%20prevents%20your%20images,from%20visitors%20on%20another%20site.