red card foul against one player, but not the other even though both collided?

How does that work?

What about that technicality Poppet keeps citing in how the VAR playback was supposed to be shown to the center ref? If he violated the rules, does that mean the red flag must be voided or still maintained?

I don't know anything about that stuff, but it seems that if one ref broke the rules in deciding a question of a player's rule breaking, the favor goes to the player and any penalty is tossed.

Yes? No?