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

Results forsecure.com.renderproxy.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-02-15T02:32:55.42	2021-02-15T01:32:55	2021-05-16T01:32:55	ww25.secure.com.renderproxy.com	ww25.secure.com.renderproxy.com	C=US, O=Let's Encrypt, CN=R3
2021-02-15T02:32:55.277	2021-02-15T01:32:55	2021-05-16T01:32:55	ww25.secure.com.renderproxy.com	ww25.secure.com.renderproxy.com	C=US, O=Let's Encrypt, CN=R3
2020-01-13T13:00:42.288	2020-01-13T12:00:42	2020-04-12T12:00:42	secure.com.renderproxy.com	secure.com.renderproxy.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-01-13T13:00:42.102	2020-01-13T12:00:42	2020-04-12T12:00:42	secure.com.renderproxy.com	secure.com.renderproxy.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3