I played through the demo level and took the survey. I don't want to come off as too negative so first of all, I think this has good ideas for a bullet hell shooter. My main critique is that the rebound system feels like it's punishing me for using it. It's hard to time and all I get for it is flung into more bullets. I don't get invincibility or some kind of power up. I get a score multiplier but a casual player doesn't care about that. Using locks out out of using the dash for a period of time.
Also since you are using Unity and in your credits you don't list this under the packages you are using, have you seen:
https://assetstore.unity.com/packages/tools/bulletml-for-unity-16206
Might be useful to you.