Test: Setting - Maintenance - Primary Microphone. During the test, press from the outside on the back of the cover near the USB input or primary microphone
Solution: Open the cover.
Fix one or two thin cardboard strips on the bottom module with adhesive tape. The disturbance disappears almost completely.
Unfortunately, after inserting the cardboard strips, the USB plug presses against the case, so that the problem occurs again, so I cut out the case at the USB hole a bit and stuck the case with adhesive tape. Doesn’t look great, but it works!