There appears to be a recurring bug problem with the USB Type-C audio output on both Pixel 2 and Pixel 3 families of devices that results in an audio feedback loop when headphones are worn during a phone call. That's based on a tip received by Android Headlines, pointing to a recent addition to Google's Issue Tracker bug reporting tool as well as to at least one of the forums that the bug cropped up in last year. As noted in the report, the issue appears to be caused by an audio feedback look between the inline microphone and the earpieces of a device. For clarity, a feedback look happens when audio is fed directly and consistently back into a receiving or recording device, causing it to be increasingly amplified until a high-pitched tone or, in this case, static occurs. That doesn't appear to be fixed by any current workarounds either and occurs regardless of the listening configuration - regardless of whether the newer or old version of the USB Type-C to 3.5mm audio dongle is used and with the USB-C Pixel Buds.
Background: As alluded to above, the initial reports of a problem can be traced back at least to the Google Pixel 2 and Google Pixel 2 XL, with an almost identical problem present on those handsets. A fix was eventually provided via a patch that appears to have fixed the problem in all audio except for phone calls, which appear to still be creating the feedback effect albeit to a lesser degree. Prior to that, a workaround had been put forward on Google's Pixel User Community forums and that does appear to provide some temporary relief for the problem but is not a permanent fix since the problem comes back. Moreover, the fix requires users to activate and adjust settings found in the hidden Developer menu - unlocked by navigating to Settings, the 'About' category, and then tapping the build version number several times before returning to the main settings menu. From there, users need to enable the "Disable USB audio routing" option for at least ten seconds before re-enabling the setting. Others have indicated that only works if a restart is performed between turning the setting off and then on again.
However, that solution presents further problems of its own since toggling settings in the Developer options can have unintended consequences that won't be easily rectified by the average user. Although the settings are present on every Android OS-based smartphone, they are simply not intended for use by most owners of a given Android device. Meanwhile, these aren't the only reported issues being seen in the newest addition to Google's Pixel line-up either, with reports stemming effectively across the gamut of possibilities. Among the most recent of those, users are now reporting that the devices are overheating while charging and while using the device's camera for extended periods of time. That's causing device shutdowns and the loss of some features as the handsets struggle to maintain a safe operating temperature. With that said, as with many of the more recent reports, those other problems don't appear to be anywhere near as prominent as the audio port feedback has been.
Impact: As of this writing, the reports also suggest that it is most likely not the USB Type-C adapter or bundled headphones that are ultimately the cause of this latest malfunction. The adapter and headphones have been tested with other devices, such as the LG V30, Samsung S8 Plus, and Moto Z2 Force, by at least one user and didn't exhibit the same feedback during calls made with those. So this appears to be a problem specifically present in the phone-related codebase for the devices themselves. For the time being, Google does not appear to have addressed these most recent reports of audio problems associated with the USB Type-C audio output in its Pixel-branded handsets.