A post on kbinMeta states that “Lemmy.ml is blocking all inbound ActivityPub requests from /kbin instances.” More details here, but the theory is that – rather than defederating – lemmy.ml returns a 403 ‘access denied’ message in response to any inbound requests from a user agent with “kbinBot” in the string. Upvotes, comments, and boosts don’t seem to be going through. However, it appears that lemmy.ml still federates information outbound to kbin instances.
I’m wondering if anyone here knows what is going on and why it might be happening? Federation between Lemmy instances and Kbin instances seems to be a selling point for both, so I’m sure others using both services are curious as to what’s going on.
This is just pure speculation, but there was a recent DDOS against some Lemmy instances. Perhaps whoever was doing the DDOS was using “kbinbot” as their useragent, and this block was just a mitigation?