Comment 7 for bug 1995201

Screen sharing with RDP was indeed advertised with the Ubuntu 22.04 release, because it is part of GNOME 42 (see the release notes).
This uses the RDP backend in GNOME Remote Desktop (g-r-d) and has nothing to do with xrdp, which you apparently installed additionally.

With the extra installation of xrdp, you basically fucked up your system, since both g-r-d and xrdp are RDP servers and they are fighting over the RDP port (3389).
Screen sharing with g-r-d is literally a one-click-experience, meaning it just needs to be turned on in g-c-c. g-r-d is also not limited to x11 and works in Wayland too.

What you did here was mixing g-r-d with xrdp (same with the links you posted) and blaming this on Ubuntu. This is a classic example of a PICNIC issue (Problem In Chair, Not In Computer).

I suggest you to look up what the RDP protocol is (you apparently don't know (protocol vs implementation(s))), and look into the respective Ubuntu help, as it tells how to connect to an RDP server (and especially g-r-d) with an RDP client.