Ipad 7th gen microphone issues

Has anyone had issues with the mic not working on the 7th gen ipad? We bought an iPad on 20/03/20 and had issues one month later with this problem, sent to Apple who sent a replacement iPad! Tonight the same issue has occurred on the new iPad? Is this a common issue? What could be the problem? Callers can’t hear me on FaceTime and voice notes not picking up my voice?

thanks