To support multiple sites per IP the browser has to send DNS name of the site to the web server. Moreover, since certificates that the server uses for encryption depends on the site name, the name cannot be encrypted within HTTPS. So the browser sends the name in clear when initiating the connection. This is called SNI, server-name-identification.

It is possible to encrypt SNI, but most sites do not support that as the setup is non-trivial and error-prone.