Hello,
Do you change the code in theme files wp-content/themes/xstore? You will lose the changes in files after every theme update. If you want to make any changes use child theme https://xstore.helpscoutdocs.com/article/32-child-theme don’t make changes directly in the parent theme files. Also, update the theme first and then update XStore core plugin to the latest versions, don’t update only the theme or only plugin because specific theme version requires specific plugin version that mentioned in the changelog https://xstore.8theme.com/update-history/
Regards