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

Results fordevelop.experience.s2r.mx

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-03-23T17:19:50.135	2020-03-23T16:19:49	2020-06-21T16:19:49	light.church	develop.experience.s2r.mx	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-03-23T17:19:49.931	2020-03-23T16:19:49	2020-06-21T16:19:49	light.church	develop.experience.s2r.mx	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-24T01:31:07.474	2020-01-24T00:31:07	2020-04-23T00:31:07	research.runtime.dev	develop.experience.s2r.mx	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-24T01:31:07.294	2020-01-24T00:31:07	2020-04-23T00:31:07	research.runtime.dev	develop.experience.s2r.mx	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-23T23:37:12.691	2020-01-23T22:37:12	2020-04-22T22:37:12	develop.experience.s2r.mx	develop.experience.s2r.mx	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-23T23:37:12.514	2020-01-23T22:37:12	2020-04-22T22:37:12	develop.experience.s2r.mx	develop.experience.s2r.mx	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3