The art is just superb, really striking palette.
As some others mentioned it can be a bit hard to see the warning that everything is about to change color, especially when things get a bit hectic. That can make some of the times the colors shift feel a bit unfair. The challenge curve is steep but that's par the course for these types of games. Really well made game, definitely a stand out!
Random side note: I had no clue about that unity bullet hell repo, we had a similar gameplay mechanic with our bullet-hell game and basically spent a few days rebuilding that same system lol might have saved us some time (and perf worries lol)