I see a yellow dot on top of the signal icon, how to make it disappear??

If you see orange or green indicators in the status bar 

With iOS 14, you might see an orange or green indicator in the status bar on your iPhone. These indicators appear when the microphone and/or camera are being used by an app.

• An orange indicator  means the microphone is being used by an app on your iPhone.

• A green indicator  means either the camera or the camera and the microphone are being used by an app on your iPhone.

That's by design (using iOS 14 or later), and there are no options/settings to make them disappear.

You can submit your comments/requests to Apple directly, using this link:--> Apple – Product Feedback - iPhone

Regards

Giulio

See this support article:--> About the orange and green indicators in your iPhone status bar - Apple Support

Regards

Giulio