On JDK19 with Linux ja_JP.eucjp locale,
System.getenv() returns unexpected value if environment variable has Japanese EUC characters.
It seems this issue happens because of JEP 400.

Please check following output.
================================
$ locale
LANG=ja_JP.eucjp
LC_CTYPE="ja_JP.eucjp"
LC_NUMERIC="ja_JP.eucjp"
LC_TIME="ja_JP.eucjp"
LC_COLLATE="ja_JP.eucjp"
LC_MONETARY="ja_JP.eucjp"
LC_MESSAGES="ja_JP.eucjp"
LC_PAPER="ja_JP.eucjp"
LC_NAME="ja_JP.eucjp"
LC_ADDRESS="ja_JP.eucjp"
LC_TELEPHONE="ja_JP.eucjp"
LC_MEASUREMENT="ja_JP.eucjp"
LC_IDENTIFICATION="ja_JP.eucjp"
LC_ALL=
$ cat Env.java
public class Env {
    public static void main(String[] args) throws Exception {
        for (String s : args)
            System.out.println(s+"="+System.getenv(s));
    }
}
$ export DATE=`date`
$ echo $DATE
2022年 4月 23日 土曜日 22:33:29 JST
$ ~/jdk-17.0.2/bin/java -showversion Env.java DATE
openjdk version "17.0.2" 2022-01-18
OpenJDK Runtime Environment (build 17.0.2+8-86)
OpenJDK 64-Bit Server VM (build 17.0.2+8-86, mixed mode, sharing)
DATE=2022年 4月 23日 土曜日 22:33:29 JST
$ ~/jdk-19+b19/bin/java -showversion Env.java DATE
openjdk version "19-ea" 2022-09-20
OpenJDK Runtime Environment (build 19-ea+19-1283)
OpenJDK 64-Bit Server VM (build 19-ea+19-1283, mixed mode, sharing)
DATE=2022? 4?? 23?? ?????? 22:33:29 JST
================================

When I wrote jtreg testcase, I found ProcessBuilder had same kind of issue.