Just a word of caution: Non-peer reviewed, non-replicated, rushed-looking preprint, on a topic with a long history of controversy and retractions. So don't get too excited yet.
I would also like to know. Apparently there were some proofreading errors etc. Someone in reddit explained that rushing the publish might be explained by wanting to stake the claim and get the ball rolling on reproducing the results as fast as possible.
Honestly as someone who is also in research, that is pretty understandable. Preprint papers are all subject to peer review and editing after the fact, but are a good opportunity to stake your claim on a big discovery before someone else can. Preprints are inherently not final versions and I guarantee that the mistakes will be caught before publication.
As someone that no longer has access to university library's journal subscriptions, I very much support publishing these in a openly accessible manner.