This is not the algorithm being audited, it's the key. Telegram's complete algorithm is auditable, including the open source client apps. Server code is always unverifiable, so let's not bring that up.
Secondly, WhatsApp channels and large groups (copied from Telegram) are not encrypted in any way (cmiw), as opposed to Telegram's MTProto 2.0 Cloud encryption. The app is completely closed-source even with all their claims of privacy and its TnC even discourages you from reverse-engineering it.
WhatsApp Communities are indeed E2E encrypted. About channels, why would you want a channel to be encrypted when you are just a follower and cannot communicate back? In fact WhatsApp's guidelines explicitly state the following:
> Channel updates should be used to share information with followers and viewers, not as a way for admins to communicate back and forth.
This is not the algorithm being audited, it's the key. Telegram's complete algorithm is auditable, including the open source client apps. Server code is always unverifiable, so let's not bring that up.
Secondly, WhatsApp channels and large groups (copied from Telegram) are not encrypted in any way (cmiw), as opposed to Telegram's MTProto 2.0 Cloud encryption. The app is completely closed-source even with all their claims of privacy and its TnC even discourages you from reverse-engineering it.