News Feed reach for posts by Facebook Pages (brands, organizations, artists) is decreasing. Facebook is relying increasingly on paid advertising to manage the flow of Page post content to users.
“Every Page on Facebook wants everything they post shown to everyone… There simply isn’t room for everything, and the competition for feed space is intensifying” — TechCrunch
But as a user you can always still select “Get Notifications” or “Add to Interest Lists…” for Pages you choose — this ensures updates get through to you whether or not they’ve been advertised or sponsored: