What's more alarming to me is that they (the jabber operators) seemingly stopped caring about it. Whatever this intercepting proxy did (including from the sound of it, spoofing ACME challenges from their domain to get a certificate) could be illegal and they didn't even attempt to do anything about it, AND they are assuming that continuing to use the service after the attack stopped is somehow safe now.

Either they are grossly negligent/incompetent (IMO unlikely given the extent of their research), or they knew it was intercepted on purpose (either by law enforcement, the provider itself or one of their upstreams) and intentionally aren't saying so. They could also be withholding or lying about any number of things, including the exact response from the hosting providers.

interesting.

I am kind of shocked because I really got positive feedback of hetzner from what I heard from people.

I need to post about this on r/vps and hear about people's opinion.