Most adblockers are also capable of blocking of blocking whatever PirateBay is using to browser mine. From what I've gathered,
the Chrome add-on No Coin should block the miner as well, if you trust Chrome add-ons; just a few days ago the Hola VPN add-on was hacked and the add-on was modified to monitor a VPN user's MyEtherWallet activity.
Pretty well known fact. However, I don't see the point of browser mining, as the hashrate is so low that thousands of PCs equate like 1 GPU.
They still supposedly need income to run their site, and PirateBay themselves stated that the entire reason why they started browser mining was because ad income wasn't enough to support the site. In this case, PirateBay does have thousands and thousands of users that all contribute to mine coins, and with enough users they're likely making a sizable amount of crypto. Pre-fork and ASIC XMR was GPU mined as well as CPU mined by botnets, and botnets still made a decent amount of coin even though a single Vega card hashed significantly quicker than any pre-ASIC GPU or ASIC.
