Adjust the win condition of the new defuse race game mode to include a short after plant timer (~20 seconds?), so you wouldn't win the round instantly upon completing the emp. This would allow the other team to un-plant the enemy emp, and be able to possibly win by planting and holding their own emp. This would also let the team who killed the entire enemy team win even if the enemies planted (you would need to still un-plant their emp).

This change would allow much needed potential for flanking and drone usage, as if you do either in the release state of the mode, your team is basically down a player, because they can't contribute if the other team is already planting. This playstyle is made even worse as most layouts are one-sided. Spring mines will also have better use for denying flank and un-plants.
This change would also lessen utility spam, because you'd want to save utility for un-plant denial.

This would still allow the advantage of the team who planted first, as they win as soon as the timer is up. This would also increase the average round length to what I assume was expected (the average round I've played ends almost as soon as is possible for the emp to be planted, even though the max time is set for 2:30).

For fine tuning: timer length, un-plant speed, and whether the timer resets or not upon un-plant can be adjusted.