https://github.com/OpenPrinting/cups/issues/465
https://github.com/OpenPrinting/cups/commit/cd84d7fde692237af4996d4a0e985a3eb4a293f0

From: Michael R Sweet <michael.r.sweet@gmail.com>
Date: Mon, 5 Sep 2022 09:20:03 -0400
Subject: [PATCH] The OpenSSL code path wasn't loading the full certificate
 chain (Issue #465)

--- a/cups/tls-openssl.c
+++ b/cups/tls-openssl.c
@@ -1055,7 +1055,7 @@ _httpTLSStart(http_t *http)		// I - Connection to server
     }
 
     SSL_CTX_use_PrivateKey_file(context, keyfile, SSL_FILETYPE_PEM);
-    SSL_CTX_use_certificate_file(context, crtfile, SSL_FILETYPE_PEM);
+    SSL_CTX_use_certificate_chain_file(context, crtfile);
   }
 
   // Set TLS options...

