Hmm, I am not completely sure what the website is trying to say (there is soooo much text and it's quite unreadable). But it feels like it says "it is hosted on US servers, so it's baaaaad".

The thing is, it seems to be end-to-end encrypted with MLS, which means that the servers cannot decrypt the conversations. Probably some metadata are leaking (which IP is in a call with which other IP), but that's a different threat model. Metadata is always a harder problem.

Now I don't know if Proton knows which users are together in a call, or if it's just leaking IPs. Maybe the article says it, but I didn't have time to decrypt it :-).