Saw your post on Bluesky and wanted to try the game, but ended up playing all levels (I did it on Firefox with no problems other than the new page).
The camera is indeed too jerky and it doesn't help that the cute little cube starts moving too fast (I guess you aren't using a lerp for movement?). Instantaneous movement is a valid game design choice, but the camera suffers from it: have you tried enabling position smoothing? Even just a little can help a lot. That said, turning camera movement off is definitely better; maybe it should be off by default.
Gameplay wise, I think the higher jump after dashing into the ground is underutilized: after the tutorial, I needed to use it only for the last jump in the last level (I for sure missed some speedrun skips that could use it, though). Also, the tutorial for it is a bit misleading, as it requires a dash upwards after it, which made me think I was doing it wrong by not jumping higher: maybe you could remove the need for the upwards dash by putting spikes on the ceiling and using the fact that the higher jump is shorter than the dash.
As for nitpicks, one of the messages at the top of the screen came out as "null" (don't know if is intended) and, finished the last level, the "next level" button does nothing (you could rig it to take to a win screen or just the level select screen).
I like how the cube is cutely animated and the level design was pretty good! I liked how it offered multiple routes and the secret on level 6 (which I actually reached a couple of times by mistake, so maybe it could be made a little more difficult).
Also, thanks for putting key rebinding: I greatly prefer WASD to arrows, so it always irks me when a game force me to use keys I'm not accustomed to.
I had fun! You could for sure work on it a little more and it would become a great little game, but even just as Godot practice, I think it served its purpose :)