Hi rajaayaz, it could be true - and your browser will be loaded with ads and pop-ups, or it could be loaded with viruses. If it's the viruses then nevermind your PC being infected, I'd be more concerned about your credentials to wallets and actual mining websites.

The choice is truly yours and it could be either one of the above, I don't know but I've seen hacking and it's not pretty, stick to a trusted browser you know and a platform that's trusted.