Google is in the unusual situation of receiving a lot of blatantly invalid DMCA takedowns. Like, a movie studio (or a company under contract to them) will do a Google search for something broad, like "download game of thrones", and issue a mass takedown for every single link that shows up, often without even
looking at the links. So a lot of perfectly legal content (e.g, a news article that says "Game Of Thrones is one of the most commonly downloaded TV shows") gets swept up, and Google is being good enough to spot those and reject them.
(Sometimes the DMCA agents screw up even worse. For instance, there's evidence that some of them forget important keywords sometimes, and end up issuing a takedown on all the top links for searches like "download".)