It can be anything! An apex, subdomain, or even a URL.

Results forcom.specialize.vc

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2022-12-23T04:02:49.074	2022-12-23T03:02:48	2023-03-23T03:02:47	ancientinsighttoday.com.specialize.vc	ancientinsighttoday.com.specialize.vc	C=US, O=Let's Encrypt, CN=R3
2022-12-23T04:02:48.855	2022-12-23T03:02:48	2023-03-23T03:02:47	ancientinsighttoday.com.specialize.vc	ancientinsighttoday.com.specialize.vc	C=US, O=Let's Encrypt, CN=R3
2022-11-03T17:26:23.638	2022-11-03T16:26:23	2023-02-01T16:26:22	lbibeachhome.com.specialize.vc	lbibeachhome.com.specialize.vc	C=US, O=Let's Encrypt, CN=R3
2022-11-03T17:26:23.228	2022-11-03T16:26:23	2023-02-01T16:26:22	lbibeachhome.com.specialize.vc	lbibeachhome.com.specialize.vc	C=US, O=Let's Encrypt, CN=R3