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

Results forgit.lowkeys.de

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-08-28T08:28:21.384	2021-08-28T07:28:20	2021-11-26T07:28:19	git.lowkeys.de	git.lowkeys.de	C=US, O=Let's Encrypt, CN=R3
2021-08-28T08:28:21.227	2021-08-28T07:28:20	2021-11-26T07:28:19	git.lowkeys.de	git.lowkeys.de	C=US, O=Let's Encrypt, CN=R3
2021-06-26T13:28:03.672	2021-06-26T12:28:03	2021-09-24T12:28:02	*.lowkeys.de	*.lowkeys.de	C=US, O=Let's Encrypt, CN=R3
2021-06-26T13:28:03.541	2021-06-26T12:28:03	2021-09-24T12:28:02	*.lowkeys.de	*.lowkeys.de	C=US, O=Let's Encrypt, CN=R3
2021-05-13T08:06:34.847	2021-05-13T07:06:34	2021-08-11T07:06:34	git.lowkeys.de	git.lowkeys.de	C=US, O=Let's Encrypt, CN=R3
2021-05-13T08:06:34.606	2021-05-13T07:06:34	2021-08-11T07:06:34	git.lowkeys.de	git.lowkeys.de	C=US, O=Let's Encrypt, CN=R3