the only "unfair" would be when there are balance problems, leaving aside if it currently exists or not.
After that, sometimes we have an advantage and sometimes we don't, we can adapt that a little knowing how the metagame works.
If we play large units ... Igni, Scorch, poison will be our worst encounters, if we play tokens, that would not be a problem.
And like every card game, count the cards we get, it can happen that the best are in the deck at the end of the game if we do not have how to secure them.
Completely fair....... Chess is the only sure thing, there are many variables in card games.