nostr:npub1f6smm2esp8gev5chwmdq9aac398fnjphruzslpugv9exdh76wfdschy8ra 

The alt text is there, but unfortunately there's not an easy way of seeing it on mobile browsers. The iPhone has the same problem. AFAIK the only easy way is using an app instead of the website.

Developers seem to have forgotten the alt text exists 😢  One theory about this is that originally the alt text was used by sighted people in the days of slow internet connections to know what an image was as it loaded. When speeds increased, sighted people paid less attention to alt text.