Thanks! I see it now too. Very sharp eye you have. I also cannot explain this sudden drop in amounts of bets placed. Could it be a whale dropping out? Are there any other possible explanations?
This might not be the reason for the sudden decrease in bets, however minimum bet size is limited so smaller bettors will must reduce the number of bets if they are to bet within their means.
Isn't minimum bet already very low? Something around 0.01 btc?
If yes, then is it not more likely that gamblers just reduce the amount of btc they bet, instead of playing less?