Restore a Minecraft Java world

Record the server version, mod loader, plugin versions and level-name in server.properties. Confirm the backup opens and make a separate copy of the current server directory.
Stop the server cleanly. Restore the matching world and dimension folders into a test copy with the same server software. Preserve folder ownership and permissions.
Start the test instance, inspect the logs and join to check the spawn, dimensions and player inventory. Promote the tested copy during a maintenance window. If checks fail, keep the original directory in service.