Do you even know what Reflection NAT is?
And when to use it?
Let me give you an example.
Imagine you have the FQDN “homeassistant.u-r-not-the-sharpest-tool.in-the.box” ,which definitely fits here, the underlying IP address which point to this is 123.123.123.123, but in fact the NAT IP is 192.168.178.254
When you now try connect from Internal Subnet 192.168.178.0/24 to this, some routers forbid that. Because it would give you the Internal IP back and not the external one! And imagine what happens then with the usage of the fancy domain you pay for and the certificate?
To circumvent the technique would be Reflection and Hairpin NAT.
Examples:
So, yes it is!
Sometimes it is better not to answer and blame others for obviosuly own lack of knowledge, though.
And again. A public domain and certificates from a public CA are not needed to make this work.