From a couple of things I’ve seen I would say there is the ability for deck strength to be assessed from strong card combinations. For example, in the small selection of decks that are available so far on TableTop Simulator or as print-and-play (anyone PM me if you’re curious and want a link!) there’s a deck called The Guild-keeper of Doomwind which the community has found is very powerful.
It contains 3 copies of a (common) Untamed creature called Hunting Witch which gives the player an æmber every time they play another creature to their battleline; that’s potentially 3 æmber for each creature – or at least a continual supply of Hunting Witches to constantly be earning æmber. As well as a (common) Dis action, Arise!, that allows the player to pick a house and retrieve all the creatures from that house from the discard pile – keep that in your hand and you can bring back all your Hunting Witches (and the rest of your Untamed creatures you’ve played so far).
As you can see, that particular card combo is fairly powerful. So maybe the decks can be assessed and if they have certain combos present, when you scan the QR code into the app it could tell you that hey this is a pretty nuts deck so you can start your game with 5 chains or whatever. This number could be adjusted as combinations are discovered (or countered!) to balance decks out.
But yes, I agree that from statistics alone it might be hard to rule when something is an inherent deck bias or player ability.