The "WhatsApp Encryption Overview" technical whitepaper  had the following text removed between revisions:
"At no time does the WhatsApp server have access to any of the client's private keys."
> The WhatsApp server has no access to the client’s private keys, (...)
>All chats use the same Signal protocol outlined in this whitepaper, regardless
of their end-to-end encryption status. The WhatsApp server has no access to
the client’s private keys, though if a business user delegates operation of their
Business API client to a vendor, that vendor will have access to their private
keys - including if that vendor is Facebook.
Not sure if the facebook exception was there in the previous version.
This is craftily ambiguous.
A copy I had downloaded on 29 July 2020