They started adding jQuery Migrate in WordPress 3.6. Most up-to-date frontend code and plugins don’t require
jquery-migrate.min.js. In most cases, this simply adds unnecessary load to your site. You can see this running if you launch Chrome Devtools console.
Remove jQuery Migrate
Follows the steps below to remove jQuery Migrate. Note:
jquery-migrate.min.js is no longer enabled by default in WordPress 5.5 and higher.
Click into the Perfmatters plugin settings.
Under the “Options” tab and “General” sub-navigation menu, toggle on “Remove jQuery Migrate.”
Scroll down and click “Save Changes.”
We have had some reports from those using page builders and Visual Composer that this sometimes breaks images. If you see this, we recommend leaving jQuery Migrate enabled.