Way too hard and the spikes should have a smaller vertical hitbox. Definitely add more leniency, like an extra dash for each level so that players can be more creative rather than to be forced to do the only solution of the level that's specifically extra difficult.
Definitely add a reset button that spawns the player back to the spawn point or the start. Not having this was especially annoying at that one very vertical level, where if I failed the first jump, the timer kept ticking.
The UI also started bugging out and it started giving me ghost dashes, which eventually moved the timer, and my dash slider out of bounds.
I stopped playing at the slow moving platforms level after seeing that dash between two rows of spikes. That's the level where it started feeling incredibly annoying to continue because the whole level was based on game time and the platforms started going out of sync to eachother, which later would cause me to use extra jumps that would probably make the level impossible because in the previous levels, there were no dashes to spare.
Something that these timing based games need are indicators whenever something can be done. The grappling points should light up when the player is hovering over them and the player should flash/make a sound whenever the dash is fully charged. These small details make a platformer feel WAY better.
It's still very impressive for a first game jam project, so congratulations!