You should also see when they are released, and for all the latest games they have 96,00-96,20%
So most likely that's what they will use in the future.
I'm looking at their website and according to that their 3 latest releases are Esqueleto, Flux and Magiscious. Two of them have 97,6 and one has 96,2.
I just don't see the trend towards lower RTP that you are seeing.
Maybe the casino you play at are releasing them in a different order than they were released from Thunderkick?