I'm runnning chimaera.

A few weeks ago I started having odd audio problems.

(1) Suddenly my external speakers, plugged into the stereo out socket
on my laptop, stopped working. They work find when plugged into my phone.
I now use the laptop's own built-in speakers. Audio quality an volume suffer.

(2) firefox has started producing high-pitched squeaky voices on zoom.
Other services, such as jitsi and youtube work fine.
And zoom audio works on chromium.
Though (long-standing problem) zoom gives mo video on chromium.
I'm now using audio on chromium together with video on firefox.

Any ideas?
Could there be some common cause here?

-- hendrik