( I tried to comment on this right before Itch went out for half a day; bare with me.)
That was cool! It started simple, but the last two levels built on the mechanics in cool ways. The time pressure on the moving cloud level was fun (as was the bit at the end of it with the two gems). The 2 / 3 lines of clouds with gems in the final level was a cool platforming challenge.
The only bug I noticed was, in the first level, being able to finish the level by hitting the platform right below the flag.
Great work!