ffmpeg rtmp stream fails when using authentication

[deonstz]

Question

I found a comment referring to this problem (#2056). I still have the same problem and my first time a needed this feature.
I need to stream the video file to a commercial server and the url I am using is:
ffmpeg -i mnbc3.mp4 -c copy -f flv rtmp://afreesrv2.mangomolo.com/nbcsrc/?username=who?password=somestring
The error I am getting is: Unknown connect error (unsupported authentication method?)
Anyone can enlighten me why this fails?
Tested on Ubuntu 22.04.5 LTS, ffmpeg version 4.4.2.