To accurately determine the TLS version of your load balancers, it is recommended that all tests are run against the default domain of your application ([your-application].prod.acquia-sites.com). Using other custom domains, which may or may not be routed through other services (for example a CDN such as Cloudflare) may not garner accurate results.
It is recommended that you use an online tool such as Qualys (https://www.ssllabs.com/) for your tests or alternatively you can use the command line tool nmap like so:
nmap --script ssl-enum-ciphers -p 443 [your-application].prod.acquia-sites.com