Yeah, adding more detail terms about the "bonus cancellation" will be good for both players and duckdice. Terms like what will happen if a player decide to cancel the bonus when....(may happen in some scenarios)
One more thing that I missed from this deposit bonus terms, if a player take the bonus so which balance will be used first? The initial deposit first or the bonus first?
Just adding a 'last-warning' or one more confirmatory pop-up would do it.
Regarding you question about the bonus, if you deposit 1 btc and activated bonus(120% bonus for example), your total starting balance will be 2.2btc. So both original depo and bonus are used at the same time