That is a very interesting main mechanic. I like how this also makes bullets not just a risk for your health, but more importantly, for your streak. Overall a very good game, but some constructive criticism:
The player feels a bit floaty, you should decrease the acceleration and deceleration time. Also the health bar is no longer visible after you die once (barrel got me).
The game freezes for a bit when you fire the laser for the first time, and when something explodes for the first time. This is due to shader compilation, which happens when a new shader or particle proceess material becomes visible. The way I fixed this in our game (also made in Godot) was to put every material in a tiny SubViewport that renders them once, forcing compilation at the start so it doesn't happen during gameplay.
Congrats on making a cool game!