Do we know the advertised RTP?
The RTP is not advertised.
Would it make a difference if the actual payback was around 98%? Even if it was artificially produced? After all, you would still have a decent payback at the end of the day.
No. It's advertised as a card game, if I wanted to play some kinda funked up slot, I would. You might as well say to someone playing double-zero roulette for $100/spin that they'd get better odds on the high-limit slots. Sure they would, but they didn't sign up to play slots, they want to play roulette, and it should operate fairly, we shouldn't need to ask if each segment of the wheel is equally likely, if each card is equally likely, it's a part of the casino's implicit contract with the player, to play fairly.
All casino games have a house edge, we know that, but just because you voluntarily choose to play a game at which you are likely to lose money, doesn't give them the entitlement to cheat. They might as well just steal your whole deposit up front and say 'well you're going to lose in the long run anyway, this just saves time'.