Thanks for your help. While removing the permission for microphone and telephone did not change anything, completely deactivating the Google App did. Since I don’t use Google Assistant, it seems to be a sufficient workaround for me personally. Scary though that the Google App seems to interact with the microphone hardware somehow, although permissions are removed. I’ll tell the support how I fixed it and that this seems to be software related. I’ll also link this thread in order to raise awareness of other people also experiencing this issue.