Steps to Reproduce:
A] Configure GS 7.1 with JDK 11 to run as a windows service.
B] Start windows service.
C] Check the manager logs.
D] It will show GMT time instead of local timezone irrespective of setting any property on UI.

A] Stop and remove old service.
B] Edit service.bat file
C] Remove -Duser.timezone=GMT; (Be careful, you need to remove ";"  and extra space as well).
D]  Also, -XX:MaxPermSize=256m this parameter has been specified twice in the file. So both entries needs to be removed along with spaces.
E] You can give it heading as, it should look like this:
if DEFINED MAX_HEAP (.\bin\windows-x64\tomcat9 //US//%SERVICE_NAME% --JvmMs 256 --JvmMx %MAX_HEAP% --JvmOptions "-Dcatalina.home=%CATALINA_HOME%;-Dcatalina.base=%CATALINA_BASE%;-Djava.io.tmpdir=%CATALINA_BASE%\temp;-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager;-Djava.util.logging.config.file=%CATALINA_BASE%\conf\logging.properties;-Dfile.encoding=UTF8;-Djava.net.preferIPv4Stack=true;-Dds.baseDir=%DS_DATA_DIR%;")
F] Install and start the service again.
G] Check the logs.

This issue (GS-17884) is fixed in GS 7.1 HF-05 already.