This is part of a hosted package. In theory, this means that the folks over at Element.io can't see the chats between you and your customers/business partners because of the E2EE. That does depend on them not hosting the software, of course, because E2EE becomes useless if the software used to encrypt data can be changed at a whim.
With the private keys on the recipient end and the browser end, it does make it easier to follow certain data privacy regulations. Whether the rather leaky Matrix protocol is considered foolproof is still an unanswered question, though; the average encrypted chat session sends a LOT of unique identifiers that shouldn't cause any trouble, but I haven't seen a recent audit of the protocol.
With the private keys on the recipient end and the browser end, it does make it easier to follow certain data privacy regulations. Whether the rather leaky Matrix protocol is considered foolproof is still an unanswered question, though; the average encrypted chat session sends a LOT of unique identifiers that shouldn't cause any trouble, but I haven't seen a recent audit of the protocol.