Home Assistant’s installer stops automatically accepting every Proxmox server certificate. Certificates trusted by the operating system follow the normal secure route; a self-signed, expired or mismatched certificate prompts the user before any credentials are sent.
The prompt explains the common self-signed setup and shows a fingerprint for comparison. Approval is tied to that exact certificate for the session: if it changes, setup stops and asks the user to reconnect and confirm the replacement. Retrying a password or entering an authentication code does not repeat the prompt for the same certificate.