Why would any enterprise use e2e encryption?
In most juridictions and industries you must be able to audit internal and b2b communication.
In most juridictions and industries you must be able to audit internal and b2b communication.
If you want audit, you then add it on separately, in a separate locked-down deployment, compartmentalised from the rest of your infra and the chat server, so that an attacker would need to pwn an audit client connected to that instead.