Waaayyy too hard right out the gate. I'm not given time to learn the mechanic before being presented with a literal wall I have to get past. The second puzzle on the other hand gives you a more controlled environment to see how the speed effects your own movement in a tangible and clear way.
I think the spikes that sink and rise would be more fair if we could see them embedded in the ground, or get some kind of telegraphing that they're about to come back up since the moment they're visible they're lethal.
Graphics look good! You get a lot of mileage out of that monochrome style. Overall I found the game kind of frustrating but I'm not really that into precision platformers.