What a WHOIS lookup shows today
A WHOIS lookup returns the public registration record of a domain name. The fields you can rely on are the sponsoring registrar and its IANA ID, the creation, last update and expiry dates, the EPP status codes, the delegated nameservers and whether the domain is signed with DNSSEC. Most records also carry an abuse contact for the registrar.
What it generally no longer shows is the name, address, phone number and email of the person behind the domain. That is a deliberate policy outcome, not a fault of the tool, and it applies to every WHOIS service that queries the same sources.