It is not hidden, but maybe they did not announced publicly. As we all can see here
https://help.stake.com/en/articles/4821738-what-is-rakeback-how-it-works-and-how-to-get-it and as confirmed by live support, the rakeback is now 5% only. The same information is also available under the VIP club page, but the information about when it is changed is available in the help center page. The article about rakeback is updated this week. Anyway, I dont understand why Stake cut it 50% off, but I think it may affect some players and may leave Stake because of this change.
Don't know what to say now, but it is a tricky move from Stake team. And they have done it really bad. The rakeback was 10% since the beginning. Suddenly they have reduced the rakeback rate by 50% without informing the users. At the same time they have increased the weekly bonus amount by 50% (up to) and announced it on the telegram VIP channel. Basically, they aren't giving anything extra. This change will bring benefits for Stake actually. The rakeback amount was promised one for every VIP user, but there is no guarantee that everyone will receive 50% extra on the weekly bonus amount.