@Myfe My bonus % is falling as well. However, I always assumed that's because you're encouraging users to keep wagering in order to keep the % up. For example I had 100% bonus, but I fell back a tier. Now it says I'm 79.1% to the next tier. I did some low-volume wagering, like 20-100 satoshi per, and then it went up 0.1%. So I think it may be working as intended. But I am PM'ing you my User ID just in case this is not intended functionality :-)
Yes, I think it is working as intended. It's a ratio of how much you claim in free rolls to how much you wager and spend on lottery tickets. So if you stop gambling and just claim free rolls then the % will go down.