Do you actually believe that this is a real feature and that it does give you a higher chance to win? I think it might be real, but it is insignificantly higher than your normal RTP. ( 0.5% to 1% better )
Have you played these games and have you seen any difference in your win percentage?
I don't trust anything the casino promises unless it is supported by a 'provably fair' mechanism and only after checking it on several examples. If there is no evidence that some games have overclocked RTP, and it is not experimentally verifiable, then there is no reason for me to trust that the casino is so good-natured that it will keep its promise, especially when everyone is lying. All you have to do is look at the supplement or food market to see that for corporations, profit optimization is more important than the truth or even the customer's health.