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

Results fortripilli.com.renderproxy.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-01-21T16:02:48.035	2020-01-21T15:02:47	2020-04-20T15:02:47	www.tripilli.com.renderproxy.com	www.tripilli.com.renderproxy.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-21T16:02:47.812	2020-01-21T15:02:47	2020-04-20T15:02:47	www.tripilli.com.renderproxy.com	www.tripilli.com.renderproxy.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-21T15:49:44.831	2020-01-21T14:49:44	2020-04-20T14:49:44	tripilli.com.renderproxy.com	tripilli.com.renderproxy.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-21T15:49:44.714	2020-01-21T14:49:44	2020-04-20T14:49:44	tripilli.com.renderproxy.com	tripilli.com.renderproxy.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3