I dont check much the total prize pool but did you mean top 4 only will get BTC reward and the rest will get free spin reward? Because rewarding only top 4 user will be quite unappetizing for new players considering how huge the wager volume of Blackjack.fun whales.
Yes , it's true that only the top 4 get BTC while the other 6 participants get free spins and this week it has been updated
now all participants 1-10 will receive USDT no free spins and prize pool reduced by 50% from the previous week
I suspect that in the near future they will update it again maybe in the next month.