Found a bug, when overlapping shades are walked into they both claim the firs block type. It also stops you from finishing the level when the green tiles hide the targets (x).
31 days ago(+2)
Them claiming the same type is intentional because there's no way to tell in which order they should claim the blocks.
24 days ago(+1)
I was so proud of myself after finding this "toothbrush" solution. Sad it doesn't work. Thanks to ennequeue's comment I could find the "correct" solution