Flutter date range picker's in between color won't change

I have a Flutter app that uses showDateRangePicker to pick a date range. When I pick a range, though, the color in between the picked dates is somehow cyan. I'm assuming it's one of the standard application colors since I haven't selected cyan anywhere myself, but I can't seem to find the right one so I can change it.

This is what it looks like

Someone please help me out!

I've changed every color inside of colorScheme and it did not change the color of the range.

Set inside your theme a datePickerTheme and overwrite the rangeSelectionBackgroundcolor:

theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        datePickerTheme: const DatePickerThemeData(
            rangeSelectionBackgroundColor: Colors.red),
        useMaterial3: true,
      ),