After trial and error, I found the answer.
Android “automatically generates” white (or black) text based on the primary color in yours styles.xml. It is rather inconvenient for Google to handle it this way, because using certain color backgrounds may still look good with white text.
resources / values / styles.xml
<style name="AppTheme" parent="Theme.Something">
...
<item name="colorPrimary">@color/primary</item>
...
</style>
source
share