By default, the following tag shows up in every WordPress install.
<link rel="wlwmanifest" type="application/wlwmanifest+xml" href="https://yourdomain.com/wp-includes/wlwmanifest.xml" />
The above link is actually used by Windows Live Writer. If you don’t use Windows Live Writer, which we are guessing you don’t, this is just unnecessary code.

Important: This feature was removed from Perfmatters in version 2.3.0 since WordPress deprecated it in version 6.3.
If you are still running on an older version of WordPress, you can add this code snippet to your site if you want to continue using the feature.
Remove wlwmanifest link
Follow the steps below to remove the wlwmanifest link.
Step 1
Click into the Perfmatters plugin settings.

Step 2
Make sure you’re on the “General” submenu.

Step 3
Toggle on “Remove wlwmanifest Link.”

Step 4
Scroll down and click “Save Changes.”