There is (or at least used to be) a menu next to people's posts that lets you stop following similar posts (or unfollow the person completely while remaining friends).
At least on the Android app, this is incredibly broken. Not only does it often not actually hide the item you try to hide, but most of the options that are available for this menu on the desktop web app are missing, so you can't actually unfollow the person 7 out of 10 times.