'Double or nothing' changed, slightly
Before when you reached day 7 you would immediately get credited with the 10 lingot bonus.
Now I just saw that you have to do 8 days before you get the lingots added and receive the notice.
No big deal (I have almost 800 lingots so it doesn't matter to me), but it's different now and it was more logical before so maybe think about changing it back?
This is on a PC, not the mobile app.
The wager hasn't changed. The discrepancy you're probably seeing is due to whether you purchased your wager before completing your streak on that day or after. The streak and wager are tied - to win your wager you have to extend your streak by 7 from the value it is when you purchase the wager.
This means if you're on day 33 and you extend your streak to 34 and buy a wager, you'll finish it on day 41. If buy a wager and then extend your streak to 34, you'll finish it on day 40.