Really enjoying this after you added it to f-droid! I love all the unique upgrades (the new one I tried today was a bit confusing, Unbounded, I thought by 'the sides are removed' the ball would emerge on the other side of the screen, which is not what happened at all, but if you want to create an upgrade that does that with the sides I think that would be fun).
I do wonder if there could be a way to temporarily disable specific upgrade options. As you add more options it can be harder to create interesting or just specific builds, depending on your luck of the draw. This is a minor concern, as games are very short anyway so there's always the next run, but it's just a thought I was entertaining. You could possibly limit the number of disabled upgrades by having each one cost a +1 to your coin combo (keeping a lower bound of +1 coins that just starts increasing once your coin combo increases above the number of disabled upgrades). That would likely be confusing for the user though. Another thought I had was rewarding the player as part of the unlocks system with occasional +1 coins to their combo, just as a flat upgrade to their ability to build score, and then they could use those specific +1 coins to trade between guaranteed higher scoring and the ability to disable upgrades (creating a way to naturally limit how many upgrades one can have disabled at once). This ability may be more complicated than you are interested in, however.
Again, just thoughts I've had. Thank you for the fun game. :)