HoloCure did it by rubber-banding the enemy's health to player damage, and enemy speed to player speed. But, crucially, both were capped so they wouldn't outscale the player, just gradually trend back towards the original difficulty curve over time after a wave change. (New enemy graphic.) And even with that soft auto-balancing, even with meta-progression upgrades normalized for Timed Mode, it was expected that broken builds would be possible when a lucky run goes off the rails.
But how could this be done within the constraints of a Jam? 🤔I suppose the most important thing is to end the game via Time Limit, like Vampire Survivors and HoloCure did, not by increasing the difficulty until the player gets overwhelmed. Then again, maybe that's a fix that would only be useful after there's more content in the game, long after the Jam is over.
Either way, good job doing so much within a short time period. 👍