Why does the cube split into separate pieces?

That is the level's re-presentation after target groups clear. The separated bars and cubes still use the same target-row order.

Are the late red/pink pieces optional?

No. They are the final target remnants shown before the checkmark and reward state.

Cube Tap Sort level guide

hard 12 colors

Break Level 22's dense color cube from gray and orange through the refreshed color route and finish the separated red/pink pieces.

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From the exposed front of the dense cube, clear gray 1 and orange 4.
After the first automatic re-presentation, follow the red/orange and blue/green groups on the newly open bars.
Inside the separated bars, take yellow/cyan from the newly open middle row, then pink/purple from the lower bar named by the refreshed boxes.
When the cube becomes isolated bars and single cubes, keep the same target-row order; do not spend buffer space on a piece that belongs to the next phase.
Clear the final red/pink pieces from the sparse lower end after their boxes appear, then wait for WELL DONE.

Colors in this level:

Gray, Orange, Red, Blue, Green, Yellow, Cyan, Pink, Purple, Lavender, Lime, Peach

Clear gray 1 and orange 4 from the exposed front of the dense cube.
After the block shifts automatically, use the refreshed row instead of the nearest touching face.
Keep solving after the main block separates; the final red/pink pieces remain part of the same route.

Board notes 5 details

Layout: The opening board is a dense multicolored cube made from interlocked patterned faces. Gray 1 and orange 4 are active, and the buffer row is empty.
Goal: Follow the re-presented route through red, blue, green, yellow, cyan, pink, and purple before clearing the final red/pink remnants.
Opening: Clear the exposed gray 1 and orange 4 faces before working deeper into the packed cube.
Danger Zone: Adjacent colors make the dense block look freely tappable; late isolated pieces remain part of the active target phase.
Mechanics: The solid cube re-presents automatically into smaller bars and separated colored pieces as target groups clear; no manual swipe is introduced. The sparse tail still shares the original target row and buffer.

Why does the cube split into separate pieces?
That is the level's re-presentation after target groups clear. The separated bars and cubes still use the same target-row order.
Are the late red/pink pieces optional?
No. They are the final target remnants shown before the checkmark and reward state.