Fun so far! I got to level 50 and had some thoughts about what I'd want for the main game. Notably, breaking blocks not just from below. Sometimes I want to come at a flag sideways or even from the top since I broke my way through. I know you want a bank mechanic off walls, but maybe if a certain force/speed is applied at a tight enough angle the block should break (and you bounce off, maybe?)
Second the game feels like Kinda Hard Golf with Breakout, but there's less strategy than the first and less arcade than the latter. I'd love to see things either be more of a strategy to solve (unbreakable blocks, hazards, etc) or power ups (moon jump, explosive break, double jump). I know you want to keep calm and relaxing, so I wouldn't crank either up too far, but something to raise stakes as your progress or speed up clearing would be nice to avoid too much repetition.
Finally, the flag does just kind of float there and you can beat the whole game without breaking except in a few cases where your path is blocked. I'd think it'd be neat if the flags were on them and the goal was to break them out of cages or something, so merely hitting them isn't enough, you have to break them out.
Cool game!