Feed behaving differently on manual and auto refresh

Hello.

A while ago, one of my feeds started having issues.
The history shows that auto-refreshes get a 403 HTTP error.
However, if I manually request a refresh I get a 200 OK.

The feed URL is Journal du Geek

None of my other feeds have this issue.
Perhaps the client request is different on each method, and that website filter them out.

I use the newsblur website interface exclusively.

Any ideas?