This has already been posted but as a lot of people are probably still unaware, riot is pulling data from your browser to use for themselves. In this case you could assume it's for "anti cheat" reasons, but there's really nothing to say they're not grabbing all sorts of other private information. Video down below with proof.
I hate to be that 'I'm quitting' guy, I've played since season 1 through all the balances and political changes some I've disliked some I've liked, but I absolutely refuse to play a game that is secretly spying on me. I now have zero trust in riot as a company and frankly I'm pretty disgusted. I've had personal medical information and private and personal conversations not to mention sensitive personal details and banking information. I honestly don't know how this is legal.
_Edit: After some consideration, I came to the conclusion that it was likely some kind of blanket check, and riot are probably not deliberately targeting the exposed information, and perhaps not even aware of it. I was too hasty in my initial judgement that it was deliberate. My mistake.
I will say however I am still a bit uncomfortable knowing it's a possibility and they could use that data without any consideration from me._