Asterisk re-invites when using Asterisk Public IP

Hello,
I have a situation where, when an INVITE is sent to the Asterisk’s Public IP (from a Proxy), a re-INVITE happens, however, if the INVITE (from a Proxy) is sent to Asterisk’s Private IP, there is no re-INVITE. I am not sure what is controlling this and would appreciate any input.

I am using Asterisk 15.3 and Channel-PJSIP.

Thank you,

What is the actual SIP traffic (pjsip set logger on) and console output? Please note you are also running an unsupported version of Asterisk that is not receiving security updates.