Good game, good color palette that matches up nicely and highlights the character position, clean character movement, clean camera transitions, the movement blocks are elegant and simple, good and simple sounds and a nice background music that doesnt dominate. I like that you have two variations of rewinding, one being restarting a level and the other being restarting the game.
Some minor critiques if you want them:
Level 3 is likely one of the harder levels due to the falling platform jumps, if you do not jump before it starts falling you will not make the jump from block 2 to 3. Additionally if you touch the sides of the blocks then they will still fall. So long as you keep this in mind when making the jump then it is still easily feasible to make the jump and luckily simply dying isnt a rewind whereas running out of time is. A good way to fix the falling block issues might be to check the player's y position versus the block's y position and to not trigger the fall unless player y < block y (or greater than, depending on game engine and orientation) or something like that; this would likely fix the block falling when touched from the side issue. As far as the block jump itself like the one on stage 3, theres several approaches and honestly fixing side-on collision might be enough.
Also I dont know if it can happen, but the timer continuing to tick down after touching the portal does introduce some anxiety, I tested it a few times and while I could get the 'rewinding due to time running out' screen to show it would still progress me to the next level; so I dont know if there is a more frame-perfect way to get it to rewind post portal touch.
Anyway good game and aside from those minor points I dont see many concerns.