Fun game type, and fun power scaling, although maybe... a little broken in a few ways.
After a certain weapons upgrade it seemed like I was no longer actually firing any projectiles, so the map began to fill with all manner of enemies. Despite also nerfing myself to nearly 0 movement speed, my HP regen (with only 30 max HP) was so high that I was able to tank everything, and pickup + graze radius were so large that I actually was no longer able to play the game because the moment I selected an upgrade, another upgrade presented itself, in an endless loop. So the run basically concluded there (that was my second one) as there was no ability to actually play with the upgrades any more lol. And I couldn't shoot anyway, but I felt like I had stumbled upon some type of win condition haha.
Also, I ran into the same problem as someone else, where even when I would hold the fire button down to reduce the likelihood that I'd accidentally select an upgrade, it still happened a few times. Other jam entries with quick upgrades like this had a similar problem; maybe a short grace period for clicks, or a button-based input method for upgrades (e.g. "1, 2, 3") could keep that from happening.
The vent and dash mechanics are pretty cool; it would be helpful for me if there was some communication about their cooldown/status on the UI so I knew when either were available. Overall, nice submission - I haven't played bullet hell games before, but I can see how with an upgrade economy like this they're pretty fun. Nice work.