Google will stop accepting new extensions that perform cryptocurrency mining on Chrome Web Store. Extensions that perform mining operations will be delisted sometime in late June. Google has allowed mining extensions under certain terms until today, Google allowed extensions to mine cryptocurrencies only if cryptocurrency mining was the extension’s sole purpose. This type of hidden in-browser mining, named cryptojacking, has become the favorite method of monetizing extension userbases by many developers. Not even Firefox is safe from such malicious add-ons.
Source: https://www.bleepingcomputer.com/news/google/google-bans-chrome-extensions-that-mine-cryptocurrencies-from-the-web-store/