Because the format is not supported

In the dashboard I constantly get because the format is not supported.

Screen Shot 2022-04-27 at 5.12.42 PM

I’m trying with OBS : error
I’m trying with ffmpeg from the command line : error

my ffmpeg commands

ffmpeg -i 1.webm -framerate 30 -pix_fmt yuv420p -c:v libx264rgb -g 60 -c:a aac -ac 2 -ar 44100 -f flv "rtmp://"

no matter what I try, I’m stuck.

-c:v I try x264, h264, anycoded = still error
i also tried -tune zerolatency -b:v 900k -x264-params keyint=60:min-keyint=60 === still error

is there a magic flag or option I’m missing ???