ADDITIONAL SYSTEM INFORMATION :
Windows 10;
Tested with Java 11 and Java 14

A DESCRIPTION OF THE PROBLEM :
When setting the property "java.locale.providers" to "HOST" the value of Calendar#getMinimalDaysInFirstWeek always returns 1, even for locales where this is not the case. For example de_De and en_GB the value should be 4.
This leads to the error that week numbers at the end of a year maybe computed to a wrong value.
E.g. in 2020 the week 2020-12-28 until 2021-01-03, should be week #53 in Germany (also in UK), but it is shown as week #1 when running int weekNumber = date.get(WeekFields.of(Locale.getDefault(Locale.Category.FORMAT)).weekOfWeekBasedYear());
Where date is one of the days in the week mentioned above.

I assume that the error is a missing/wrong implementation in HostLocaleProviderAdapterImpl, in the Method getCalendarDataProvider which implements the following snippet:
@Override
public int getMinimalDaysInFirstWeek(Locale locale) {
    return 0;
}

That returns 0 for minimalDaysInFirstWeek for all locales (later this is set to the default of 1). The macOS implementation of this class seems to have a valid implementation that calculates the value based on the actual locale.
 

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Execute the attached code snippet, while your systems format locale is Germany or United Kingdom



EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Days in first week: 4
Week # 53
ACTUAL -
Days in first week: 1
Week # 1

---------- BEGIN SOURCE ----------
import java.time.LocalDate;
import java.time.temporal.WeekFields;
import java.util.Calendar;
import java.util.Locale;

public class WeekNumberTest {

    public static void main(String[] args) {

        System.setProperty("java.locale.providers", "HOST,COMPAT,SPI");

        Calendar instance = Calendar.getInstance(Locale.getDefault(Locale.Category.FORMAT));
        System.out.println("Days in first week: " + instance.getMinimalDaysInFirstWeek());

        LocalDate date = LocalDate.of(2020,12,31);
        int weekNumber = date.get(WeekFields.of(Locale.getDefault(Locale.Category.FORMAT)).weekOfWeekBasedYear());
        System.out.println("Week # " + weekNumber);
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Start without HOST e.g. System.setProperty("java.locale.providers", COMPAT,SPI");

But this prevents getting details from the format, that differ to the standard for that locale.

FREQUENCY : always