Evolution, Security, and may be more.
But you must update a clone site in order to check for bugs
Sometimes a plugin is not updated or we have conflicts that create problems like white screen, so be carefull.
And always backup before and after the update.
google says
With each new release, they fix bugs, add new features, improve performance, and enhance existing features to stay up to date with new industry standards. So in other words, when you do not update your WordPress site, you are risking your website security and missing out on new features / improvements
