Just an idea:
What if we got bonus rounds at the end of the game that don’t count toward your win/loss? I feel like a lot of the time the Mythic battle (looking at you triple Warden Eternal inside the home base) just stops teams in their tracks. You can be doing very well with your team on the rest of the match only to get stumped by the timer while trying to chip away at their health in those close quarters.
Bonus rounds were part of the original firefights anyway. They could give us only a certain amount of times to respawn to make it a little balanced, but keep the time limit. Time limit would be important lest you have one guy standing who just trolls everyone by sitting at the other side of the map.