Google and Huawei just can’t seem to catch a breath. After the bend test videos and the more recent glass shattering, the Huawei manufactured Nexus 6P seems to be having another issue: poor microphone quality.
Users are reporting that the other person on the call is unable to hear them properly. This happens in regular voice calls and also in VoIP calls, such as in Hangouts. Some have reported it only in speakerphone mode and others in both speakerphone and earpiece mode. The issue seems to be widespread enough, with people on Google Forums, xda-developers, and on reddit having the same issue.
Google is currently aware of the issue and is investigating it further.