I'm brand new to all this (jam, game, and even itch.io), but I doubt what you said was from an error that just affected you specifically, or affects only the browser version specifically.
The inputs may have felt "delayed" to you (they did to me too by the way) because I think the engine they used might have the whole movement, especially of the one you play as, very strict on some grid or something.
No idea what engine they used by the way. But it has that sort of feeling like the movement is only on one square or another square. One row or another row, and especially when falling, one column or another column. As if there was an invisible grid of squares where each of these squares is about as big as your player, and you can either be on one square or another square, but never really in-between.
It might be because it's some RPG engine or something - but I'm not sure.
If the feeling bothered you, I think you have a valid point to notice it. I thought it was "OK" - but I think I definitely noticed it.