No — browsers have no API to inspect a remote server's TLS certificate, so the domain you enter is sent to CalcLeaf's own server, which performs the real TLS handshake and returns the certificate details.
It reflects the certificate as of the moment you click Check — a live connection check, not a cached or historical record.
Subject, issuer, valid-from/to dates, days remaining until expiration (with a color-coded warning if expiring soon), serial number, signature algorithm, and Subject Alternative Names.