Apparently one of the lemmy.ml admins was overzealous in banning all User-Agent strings that contained the string “bot”. Bans were entered for all of the individual strings containing that word which were observed in their webserver logs, which impacted kbin’s reported agent of “kbinBot”.
The issue has been fixed, and I observed that one of my kbin posts to a lemmy.ml community was successfully pushed to the original instance.
Pretty much this. It still gets a lot of flack for being operated by the developers of Lemmy, but there are a large number of users and communities that exist on lemmy.ml for no other reason than it being one of the larger original instances. Most operators of high-volume instances are unlikely to take action against lemmy.ml unless a situation develops that gives them no other choice.