Two people can't seem to talk at the same time during FaceTime calls in iPhone 12 mini

I just got an iphone 12 mini and when in a call (Whatsapp audio call and Facetime) two people can´t talk at the same time. If there´s a noise or someone speaking at the other end and i speak, they hear nothing, and the same goes for me. Any idea if it´s a phone´s problem or if it can be solved on the settings? Thanks in advance

[Re-Titled by Moderator]