If you have a case remove it before attempting Trueplay. If no case you could try closing  all apps (swipe away) and reboot the iPhone  / iPad.

I already removed the case and I also closed all the apps. Reboot was already done ;)

But I tried with my iphone 12 and it worked. So I guess a problem with the Ipad version (don’t think I have a problem on the Ipad I tested the mic and no bad noise was recorded)?

Occasionally, I’ll see this and don’t have a concrete explanation.  A couple times I was wearing slippers on a hardwood floor and they were making a little noise as I walked. Other times I had no hints. and never any real proof.

I can speculate that the iPad’s microphone has become noisy. It will be hard to explore this, but you could try streaming the iPad’s microphone output to another device and listen for noise. Another scheme would be to install some sort of audio analyzer App and check the constant background. Without any historic comparison this would be difficult to interpret because there will always be some background room noise. You could install the same App on the iPhone and compare the background noise.

Check that the mic port is clean and unobstructed. Maybe a touch of canned air?

I’d do a Trueplay with the good phone and submit a diagnostic, then again with the problem phone and another diagnostic. Get Sonos support to look at both diagnostics and see if they have any internal data they can share with you.

I had issues at one time, turning off the heating blower, then unplugging the fridge and freezer seemed to be the solution. None of them sounded that noisy to my ears.