On behalf of Gaurav Chaudhari:

When a match cannot be made directly against a recognized region/timezone from the tzdb.dat, TimeZone.getSystemGMTOffsetID() is invoked to find the GMT based offset to calculate the offset and find the corresponding time.
The native code reached in TimeZone_md.c has a bug for platforms that are not MacOS, where daylight savings is not respected.

To reproduce the issue:
TZ="MEZ-1MESZ,M3.5.0,M10.5.0" java -cp . TimeTest
with the following test , TimeTest.java
import java.util.Calendar;
import java.util.TimeZone;
import java.util.Date;
import java.text.SimpleDateFormat;


public class TimeTest {
        public static void main(String args[]) {
                Date time = Calendar.getInstance().getTime();
                SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy HH:mm:ss.SSS");

                System.out.println("Calendar.getInstance().getTime() = "+time);
                System.out.println("SimpleDateFormat = "+sdf.format(time));
        }
}

Reproducible on Linux on Z (s390x) OpenJDK18 (jdk18+38 Temurin)
TZ="MEZ-1MESZ,M3.5.0,M10.5.0" ~/jdk-18+36/bin/java -cp . TimeTest
Calendar.getInstance().getTime() = Thu Apr 28 15:55:16 GMT+01:00 2022
SimpleDateFormat = 28.04.2022 15:55:16.171

Zone ID can be set according to guidelines below:
https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html