I asked admin of my instance few minutes ago and didn’t get reply yet, but it seems your instance(mastodon.sdf.org) blocks pone.social.
EDIT: my instance isn’t blocking mastodon.sdf.org
The SDF Lemmy instance (not sure about Mastodon) has issues with federation ongoing for the last 2 weeks at least and the admins have been MIA. I’ve had to switch to an alt account
It’s best not to think of SDF admins in binary terms like “present” or “absent”. They are an undulating force which makes changes here and there and we’re all along for the ride.
… Or not, as in my case.
SDF admins have leading and guiding role of lemmy
I usually use Jerboa, so, the way that I see it is that they decided that I needed an involuntary break from Lemmy. I can’t really complain too much. If it takes too long to fix, maybe I’ll self-host, when I have time during the holidays.