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

Results forsrc.dev.bitesize.guru

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-06-17T05:21:11.348	2020-06-17T04:21:11	2020-09-15T04:21:11	locall.hitevent.com	src.dev.bitesize.guru	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-06-17T05:21:11.13	2020-06-17T04:21:11	2020-09-15T04:21:11	locall.hitevent.com	src.dev.bitesize.guru	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-04-19T18:17:06.053	2020-04-19T17:17:05	2020-07-18T17:17:05	www.uestc.icu	src.dev.bitesize.guru	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-04-19T18:17:05.838	2020-04-19T17:17:05	2020-07-18T17:17:05	www.uestc.icu	src.dev.bitesize.guru	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-04-19T15:58:46.768	2020-04-19T14:58:46	2020-07-18T14:58:46	src.dev.bitesize.guru	src.dev.bitesize.guru	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-04-19T15:58:46.525	2020-04-19T14:58:46	2020-07-18T14:58:46	src.dev.bitesize.guru	src.dev.bitesize.guru	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3