There are some vehicles that use a reduced sound quality for navigation. If this applies to your vehicle you may notice a lower quality of audio when using maps applications such as Waze, Google Maps etc and also when you split screen with another app.
Unfortunately we cannot prevent this, as this is how some infotainment systems are designed.
You can try factory resetting your device
Google Maps
If you are using Google Maps and it affects the quality of the audio. Please go to the Google Maps application then Settings>Navigation>OK Google detection>While Driving Off.
The settings on Google maps is just to the right of the search bar, if you are signed into your Google Account it may show the first letter of your name associated with your account.