Walls and doors
The breakable walls' mechanic makes weird/undesired results, also the doors are quite narrow, it's very common to get stuck.
1. At the very beginning of the run.
2. I guess I found the other side of a breakable wall.
3. I got stuck in the middle of the door until I tried a left/right shake.
4. (unrecorded) In a second maze stage I couldn't advance to the next room, and it was the only door available. Very similar to the second case.
Mechanics
This game lacks the feeling of getting better and stronger. If you look at Balatro or Binding of Isaac you keep getting stuff that makes you feel more powerful, and at the same time the difficulty increases. The mechanics that you made with the cards don't give that feeling, and I don't see an increase in difficulty with the enemies either, which they are a little to difficult since the very beginning imo, but once that you get used to their attacks' patterns, you can even avoid them.
Cards
There's no clear need to get most of them, if you get good with the basic attack and how to defeat the different enemies, you just don't need them. Why would I get a finite attack when I already have an infinite kitty?
Enemies (This is more an advice than a flaw)
It's not a good idea to use cute enemies, specially when you have cute designs that are helpful. At first I thought that the seller was a mini boss lol, the same happened with the flower, at first I thought that it was an enemy. Read the 3rd point here:
https://www.darkpattern.games/pattern/52/aesthetic-manipulations.html