After you have configured the Jamf PKI Proxy to run as a background service, the Jamf PKI Proxy logs output to syslog at the following location: /var/log/syslog. The log statements from the Jamf PKI Proxy can be searched under jamf.pki.proxy.
You can also use
journalctl to view the logging for the jamf-pki-proxy by running the following command:sudo journalctl -u jamf.pki.proxy.service