Level 5 would be difficult to balance sorry :c against the rest of the game I thought that it would be a good step up, but I'll take note of the difficulty spike, I'm still getting used to game progression in general.
If you are able to get past level 5, I'd love for you to try the electric turret that comes from the next level, as I feel like that it might make the experience against air units easier.
Thanks for playing overall though :D your feedback is always super good.