Renan, this is absolutely captivating!
I randomly downloaded it from F-Droid a few days ago, and I've played it a lot (100% unlocked and 66k high score so far, still looking for even more strategies though).
I wanted to bring to your attention a bug that can abruptly end a run: the Respawn perk may cause the ball(s) to keep floating in the void, with no bricks left to hit (it has happened twice, I suppose it's related to Respawn but can't be 100% sure).
Also, I've read in a few comments about features and stuff: I think they're not really needed and even potentially harmful. I love the game simplicity.
What could be improved, in my opinion, is that:
1. The onboarding feels weird
It took me a while to understand how the game really worked. As an example, the metrics for getting upgrades and choices is not explicitly stated in the app, I had to figure it out myself (although I later found some details on the mechanics after digging your website and other sources like HN). A quick optional tutorial may be helpful.
(Other things that were unclear to me at first were the combo and miss indicators. I've notices that the web version does a much better job at signalling misses, I guess probably F-Droid lags behind as usual.)
2. Players can't choose the initial perk
Random is great, but if I'm going for a specific strat I may have to reset a bunch of times to get something I can work with. Which brings us to...
3. Players can't easily reset the run
If I want to restart, I have to (1) find out what perk I have and (2) literally lose the ball. It would be nice to (1) know in advance the starting perk and (2) have a reset button or option in the menu.
Last but not least, there's the game balancing aspect. I feel that some perks are really detrimental to your score, which makes some strategies are clearly superior and others just not viable unless you're optimizing for some other metrics (i.e. you're speedrunning, so time becomes more valuable than coins).
An idea would be to refine the combo increase/decrease and/or upgrade system and/or the ultimate goal of the game, i.e. making top score categories for "most coins", "less time", "least bricks broken", etc.
All in all, the game is already great as is – so I hope it won't change too much.
Thanks for your efforts!