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

Results forstatic.deb.dev.deeploop.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2019-08-12T08:45:45.903	2019-08-12T07:45:45	2019-11-10T07:45:45	static.deb.dev.deeploop.com	static.deb.dev.deeploop.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-08-12T08:45:45.263	2019-08-12T07:45:45	2019-11-10T07:45:45	static.deb.dev.deeploop.com	static.deb.dev.deeploop.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-12T23:04:20.698	2019-06-12T22:04:19	2019-09-10T22:04:19	static.deb.dev.deeploop.com	static.deb.dev.deeploop.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-12T23:04:19.586	2019-06-12T22:04:19	2019-09-10T22:04:19	static.deb.dev.deeploop.com	static.deb.dev.deeploop.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3