Audio is garbled on Android 10 on speaker but not using bluetooth headset

On a OnePlus device with Android 10, audio sounds completely garbled when it is playing through the phone speaker. However, once connected through a bluetooth headset, the audio plays fine. It does not happen on standalone Mac or Windows, iPhone X, Moto G7 Play or Huawei mate 20 pro devices.
I thought it could be my game but I have setup a new project with two buttons, two audio clips and one audio source and still was able to reproduce the issue.
I have also bought a Unity plugin for playing tracks and sound FX in games but that didn’t make a difference. I have also tried changing the audio import settings from decompress on load to streaming which had no effect.
I am using Unity 2020.1.9f1 on a Macbook Pro.
Any help is much appreciated. Thx!

This is a bit old but in case you are still searching for an answer… I had the same problem. It was fixed by changing the audio settings “Dsp Buffer Size” to Good Latency. It was on Best Latency previously, for the obvious reason of trying to minimize the playback delay. However on some phones this causes buffer underrun and clicks/pops/metallic artefacts. Good Latency appears to be a workable compromise.

If you are doing the change via code (if you have a setting option for this), the values are 256 for Best Latency, 512 for Good and 1024 for Best Performance.