Even with Reroll's sprite, sound, and alert, I find that in the moment I won't notice they exist or that I picked them up, until checking later.
People unfamiliar with the game (new streamers, chat members) often are confused by Hyperboost, asking "why am I/what does it do when I'm rainbows?"
*Make Reroll powerup items bigger, maybe 2x-3x. Despite the dice sprite, they tend to blend in with XP.
*Make Boost powerups more distinct from XP. It could be larger, and have a chromatic effect, and maybe appear energetic by jittering in place.
*XP orbs could be more attention-getting, maybe occasionally pulse like they already do when they spawn, and increase their color saturation.
*Alerts at top of the screen for powerups could be bigger, maybe even 2x. For Hyperboost it could remain on screen while active, and could incorporate a bar for the remaining duration.
*For Boost, there could be a rainbow effect added to the HP bar (and Shield, with Regenerative Shields) to imply the boos