Yes, most likely there were timezone updates to Java for your geo location. Timezone is handled by Java and not JDownloader, so a Java update is required.
I recommend to backup the complete cfg folder of your JDownloader, uninstall it and install fresh again, see
https://jdownloader.org/jdownloader2 (bundled with more recent JVM)
After installation, replace (not merge) the complete cfg folder with your previous generated backup/copy