Yep that was the end. There was originally a giant boss fight against the red thing that you're chasing, with sounds and visuals and orchestras and lights and fireworks and shaders and particles... But then the jam ended :/
Completely agree with you on needing more light, my solution was going to be to have the spawners be light sources so you wouldn't have stuff spawn without seeing it, but didn't quite get to it.
The enemies didn't regrow but they kept spawning infinitely off of the red circles, if you didn't finish the red circles quickly enough there may have been dozens of them on top of each other. That was propably one of the main performance issues as well, and not explained at all by me.
Truly appreciate your feedback, I'll hopefully be able to do better in all these areas in future jams.