4c plus android 11 no audio hdmi 2k

Just installed android 11 on 4c plus.

I have no audio from hdmi 2k.
In the top right android corner, I can see an headset icon. I don’t know what it means.

Is there a fix?

I confirm, there is a bug in android: audio only comes out from hdmi 4k. No audio from hdmi 2k.

I there a way to fix this ?