I'm using streams and I can see both images here.

Checking on another browser where I am NOT logged in:

Libéllule.jpg
https://cirtensis.net/photos/lotfi31/image/f0eba35c-4ded-4a9a-b0a7-608b3a89150b
I can see this page and the 900x600 scaled image on it.

Avocette-3.jpg
https://cirtensis.net/photos/lotfi31/image/d883b7f2-04cc-4aad-bb28-a3884826cf80
I can see this page, but I do NOT see any image.

Maybe this is a clue?