The common believe is that Stake are increasing the RTP after money has been paid out in the form of bonusses, but I think that is false.
The slots from third party slot providers offer the casino 1 or 2 or 3 rtp options that they can choose from, depending on which slot it is... and the difference between them are small.. so even if they shift between them, changes will not even be noticeable to the player.
The original games are controlled by them, so they can adjust the rtp, but players will quickly pick up.. when there are periods where there are massive changes to the rtp and they will simply stop playing.
RTP is difficult to verify, because you need 1000s of bets (close to a million)... and the rtp can be adjusted, while you are testing.
I can not speak about their other in-house games, but their in-house Black Jack system is provably rigged!
Yes, to verify your experienced RTP, you need to place a huge number of bets, but not 1 million and also not 500,000 bets.
I for example made 181,000 bets and my experienced RTP is 95,5% while the advertised RTP is 99,5%!
This is proof that their in-house Black Jack system is rigged, because such a huge deviation after such a huge number of attempts is technically not possible based on the law of large numbers.