A coincidence? I played a ticket last night on Belgium to win the cards count vs Spain, I thought they would be fighting hard and committing fouls but in the end both sides took 2 cards. I should have gone overs instead of 1x2 but,,, like you said, this cards, corners bullshit,,, it is just a dice roll might as well try for high odds

This World Cup has been incredibly low on cards, especially after the first round. The tournament started out with referees throwing cards left and right during the opening matches, but right after that FIFA stepped in and told the refs to keep the cards to a minimum because they don't want star players missing any crucial knockout games.
Because of that we’ve seen a decline in cards, I expect this trend to continue and if anyone wants to take advantage of the current situation, betting the under on card markets is probably the way to go. That said I generally try to stay far away from these kinds of prop markets anyway, It almost completely depends on the specific flow of the live match making it nearly impossible to predict pre game.
Either too high, or too low, and then it puts you off,,, then we get normal game with normal cards like today morning.
Embolo for example killed Switzerland totally because even if they progressed he missed semi and final.
Cards to be avoided for knockout games,,, teams play so different and cautiously unless they are behind badly, which you only know in live like you said!