I read in the whitepaper that views on ads in active tabs alone will be considered when determining the Attention Value. How does one define a tab as active?

Does it just have to be left open? In that case wouldn't it be easy to game the system?

Does it have to be continuously scrolled across, up and down? Couldn't a bot be used to make it appear as active?

Or is Brave tamper-proof such that this kind of botting is preventable? Or would the machine learning used for determining user preferences also be used for finding out if a user is truly active?

I couldn't find the answer anywhere else, so I'd appreciate it if I got one here. :)