From level 7116 an new feature is introduced, rainbow Rapids. This is a rainbow road that moves from a fixed point to another point on the board. The rapids can move in a straight line or it can meaner around the board as it makes it's way to the exit. There can be one rainbow rapid or multiple ones, but they always have their own start and end.
See image.
The rainbows are stopped by any kind of blocker including licorice, blockers, locked cells, waffles, etc. If a blocker drops onto the rainbow it will retreat until the way is cleared again.
The rainbows can move in a straight line or they can move in different directions and it can sometimes be tricky to see the route they need to take.
The way to deal with the rainbow rapids levels is to clear everything on the board if possible so that there is nothing blocking the way.
The video below shows how the rainbow rapids levels work.
The second video shows a different level with a more complicated route for the rainbow rapids.
Videos by Cookie
Level 7119