Meetjitsi creating keys in a desktop client?

I do not have the skills to know if the following is technical
valid and accurate.

Once I read an article, I think it was about protonmail I cannot find
the article, about a man in the middle attack. The main task
is creating and exchanging the keys. About web services
software is imported into the browser. The software creates the keys and
establishes the encrypted connection from these keys.
If an attacker is able to get his software imported into the browser,
he can create the keys and monitor the transfer of data. Would it be
possible to enhance the security of meetjitsi by making a client, which handles
the creation of keys and establishes the connection on meet.jit.si? In fact
the same thing as jitsi desktop but without the sip account
requirement? Thanks.

What keys?

What keys?

Doesn’t meetjitsi create and exchange pgp like keys?