removing HSTS include from location as it is superfluous. HSTS is defined at the server level and re-adding the host at the location prevents inheritance from the advanced config include.

Per the NGINX documentation,
"These directives are inherited from the previous configuration level if and only if there are no add_header directives defined on the current level."

backend/templates/proxy_host.conf

@@ -51,7 +51,6 @@ proxy_http_version 1.1;
 
     {% endif %}
 
-{% include "_hsts.conf" %}
 
     {% if allow_websocket_upgrade == 1 or allow_websocket_upgrade == true %}
     proxy_set_header Upgrade $http_upgrade;

backend/templates/redirection_host.conf

@@ -16,7 +16,6 @@ server {
 
 {% if use_default_location %}
   location / {
-{% include "_hsts.conf" %}
 
     {% if preserve_path == 1 or preserve_path == true %}
         return {{ forward_http_code }} {{ forward_scheme }}://{{ forward_domain_name }}$request_uri;