Please can you with your colleges consider changing arena mechanics. Because it's a chaos in there. Playing in ranked you can play around - knowing what your opponent plays (faction/units/spells etc.).
In arena you can't. Literally.
All you can do is to use long/short round strategy knowing what are your finisher and what yours/opponent leader does. That's it.
From my perspective Gwent is about strategy ( and % of card replacement) and not rng. But in arena you can't - the faction restriction will solve this issue by selection leader first and then draw selected faction + natural cards. And to addition set amount of rarity cards which each player will get - this will solve "people rage quitting games" because one of the opponent have insane quality cards compared to yours.
The initial idea for arena is to be a draft, it's supposed to be chaotic, but we'll be looking into the mode overall