Domain Names are Not Protected by HTTPS

Domain names (e.g. are not protected/encrypted by HTTPS because of Server Name Indication (SNI).
SNI is an extension to the TLS protocol by which a client indicates which hostname it is attempting to connect to at the start of the handshaking process. This allows a server to present multiple certificates on the same IP address and TCP port number and hence allows multiple secure (HTTPS) websites (or any other Service over TLS) to be served off the same IP address without requiring all those sites to use the same certificate. The desired hostname is not encrypted, so an eavesdropper can see which site is being requested.

Server Name Indication
The First Few Milliseconds of an HTTPS Connection