HOW TO FIX MULTIPLIER SYSTEM ON THIS GAME MODE!
Make it like this: At start, attackers have a x1 and defenders have a x5. As Attackers capture flags, their multi goes up(to a x5) and defenders drop to a x1. This will be balanced(but would require between 5-7* ). This means that capping flags gets you points, and defending keeps your points. And If what I think is true, assuming a good average game, it'll result in a x3 for everyone, unless one side gets REAL good or has a smart tactic.
*Why: because if you have it at 7(with 2 fully uncappable spawns) or 5 with only attackers spawn unconquerable, it'll work with the 1 flag, 1 multi rule. But if you had 8 flags, you can't do this rule, but even in conquest game modes, you shouldn't have more than 7 flags anyway.