The folks behind these torrent trackers believe Windows 10 is a risk because of the extensive amount of data the OS shares, and concerns that data, even of local searches, may be shared with anti-piracy company MarkMonitor didn't do much good either to stem paranoia. Full details at TorrentFreak.
While this may sound scary, Microsoft has been working with MarkMonitor for years already. Among other things, the company helps to keep scammers at bay.
There is no evidence that any piracy related info is being shared. Still, the connection is raising red flags with other tracker operators as well. More trackers reportedly ban Windows 10 and others including BB and FSC are consider to follow suit.
“We have also found [Windows 10] will be gathering information on users’ P2P use to be shared with anti piracy group,” BB staff writes to its users.