Click the 3-dot menu button on the right side of the post, click "Hide all from <shared source>". Now if the person is sharing from <fake news site>, or <annoying meme page> you won't see it. If someone is continuously sharing nonsense from a wide-variety of sources, they get unfollowed (and they probably were not someone I selected to follow in the first place). This is impossible to manage if you are following everyone in your network (as is the default), but becomes doable if the default option is "unfollow" as enabled by this extension.
