One radical idea is to have the teams themselves contribute to the point increase. Let's say that we start with round 1 and reward 10/9/8/7 points per task.
Give 5 task tokens per round to a team, and they can choose any three or more tasks to allot those tokens to. A token will increase the value of a task's points by X, where X is some arbitrary set of numbers to be decided later. All tasks can still have a baseline growth level from round to round, but that growth can be matched by Brawler input. This complicates things by making it so task rewards aren't equal, but it adds extra agency to teams so they can bet on the tasks that they think they have the most advantage in. Challenges and bonuses would still use some baseline number, without the added value from tokens.