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.
Oh yes thank you for sharing the article. It's a bit surprising even though they often share bonuses but why has this one been changed
Even though the rakeback feature is one of the most sought after by users. Stake definitely knows the consequences and they are monitoring the impact this month.
If I have to guess, it is an impact of the weekly bonus calculation system. It is now like a combination between rakeback + lossback because the new system will give users more reward if they lose more. Of course it is just a guess, we do not know what is the real reason why Stake did this sudden change. I have to say 50% off is a bit too much in player's perspective, I believe most players agree with it.