

You don’t get control of the incoming port that way. For LetsEncrypt to issue a certificate primarily intended for HTTPS, they will check that the HTTP server on that IP is owned by the requesting party. That has to live on port 80, which you can’t forward on CGNAT.
I was very annoyed when I got this, but remembered that it’s KDE, and turning it off is 4 clicks. Proprietary software often doesn’t allow you to turn this off (easily). Windows has this “feature”, where is the setting?
I don’t think it’s a productive “feature”, but considering it can be turned off so easily I don’t consider it a complete showstopper.