Audio feedback during FaceTime/teams calls on m4 Mac mini

So the setup:

Mac mini m4, connected to a Samsung s8 viewfinity 4K monitor via usb-c and hdmi to second monitor.

sound out from headphone jack on monitor to desktop speakers

Maono pdx300 usb broadcast mic connected via usb hub on monitor.

im getting horrible feedback between the mic and the speakers on FaceTime and teams when using the Mac. It’s unusable. I get the same experience when using Ms teams, which I have to do for work.

BUT

if I plug the mic into my windows machine and the speakers into the line out on the PC - no feedback at all and perfectly usable.

i have fiddled with settings but am lost as to next step