When you open the Astro application, you can switch off your "Sidetone" under Microphone. Then everything is fine again.

The headset has 2 output and input options. Astro game and astro voice, you must set astro game as the output and astro voice as the input. Otherwise it will also use the speakers as a microphone and then you will be heard twice. Important! Also set the individual programmes, e.g. Discord.