The classic, shortly after I finally write down the question I find the solution! XD
Once again, the vibe coders at Microsoft were to blame. Apparently the quality setting was set to "phone quality" at 8 kHz. But the settings showed "DVD quality" at 48 kHz. To fix the problem, I first had to change the setting to 8 kHz, save, go back to 48 kHz and then save again. But ATTENTION: The option is available in both the modern "Settings" app and the old sound system control. However, the option has no effect at all in the "Settings", it only works in the control panel.
Hallelujah, Microsoft! You have once again lowered the already unmeasurable expectations of your software quality. "Find another job".
According to the supplier, the product on the 6th picture is sold.
Thank you for your comment, I will pass this on internally so that the images can be revised.