If your browser shows a padlock icon with no security warnings, this certificate was issued automatically via AWS Certificate Manager's ACME protocol endpoint and is publicly trusted (chains to Amazon Trust Services) without any manual trust-store changes on your device.
Host:
Served by: nginx-plus ACME module (automatic issuance/renewal)
Issued from: Amazon Trust Services (public web PKI)
To inspect the certificate chain: click the padlock icon in your browser's address
bar → "Connection is secure" → "Certificate is valid" (Chrome), or the
equivalent in your browser, and check the issuer is Amazon / Amazon Trust Services.