On LinkedIn, some of the posts in your "Feed" are ads. They carry a little indicator (by law) to tell you as much. This script looks for those indicators and hides it for you. It works by installing an event listener for when you scroll, and looks for newly promoted posts to hide.
Copy/paste the above script into your Console when visiting LinkedIn. You can use an extension to run the above script whenever visiting LinkedIn, such as "Custom JavaScript for Websites 2"