I cannot reproduce the symptom that you describe.
I tried to reproduce this as follows:
* start from a correctly working Debian 13 GNOME virtual machine
* be logged in to a GNOME GUI session as a test user (in my case it's
named "user")
* gnome-control-center ("Settings")
* -> System panel
* -> Remote Desktop button
* -> Desktop Sharing tab
* Desktop Sharing: toggle to ON
* Remote Control: toggle to ON
* How to Connect shows "Hostname: d13gnome", "Port: 3389"
* Login Details
* Username: I left it at the default "user", the Unix login name of my
test user
* Password: changed to "password123"
These steps resulted in these changes to the output of `dconf dump /`: