From this post (https://sopuli.xyz/post/15865566) on !AskMbin@fedia.io
It’s very likely related, but we also figured out that both of debounced’s (the admin of kbin.run) accounts on GitHub and Matrix were deleted last night. So there is a possibility that kbin.run is no more.
It’s showing indeed the limitations of the activitypub protocol. I’m promoting decentralization, so feel free to run your own instance. Just know that it will take some time, effort and most likely some money.