What is the long rectangle for r6c5=10?

It is the full column-5 strip r1c5:r10c5, a 10x1 rectangle.

How should the lower-left corner finish?

Use r9c1:r10c1 for the 2 clue and r9c2:r10c3 for the 4 clue.

The solved 10x9 board contains sixteen persistent rectangles covering all 90 cells.

MeowBlock! level guide

hard Target: 16 moves 16 colors

Solve MeowBlock! Level 32 by establishing the right-side blocks, protecting the ten-cell column-5 bar, and correcting the lower-left remainder.

Step 1: Anchor r10c8=3; commit top-left r10c7 and bottom-right r10c9 (1x3, area 3).
Step 2: Anchor r8c8=9; commit top-left r7c7 and bottom-right r9c9 (3x3, area 9).
Step 3: Anchor r6c8=3; commit top-left r6c7 and bottom-right r6c9 (1x3, area 3).
Step 4: Anchor r5c9=6; commit top-left r4c7 and bottom-right r5c9 (2x3, area 6).
Step 5: Anchor r2c9=3; commit top-left r1c9 and bottom-right r3c9 (3x1, area 3).
Step 6: Anchor r3c7=6; commit top-left r1c7 and bottom-right r3c8 (3x2, area 6).
Step 7: Anchor r2c6=3; commit top-left r1c6 and bottom-right r3c6 (3x1, area 3).
Step 8: Anchor r6c5=10; commit top-left r1c5 and bottom-right r10c5 (10x1, area 10).
Step 9: Anchor r6c6=7; commit top-left r4c6 and bottom-right r10c6 (7x1, area 7).
Step 10: Anchor r6c3=5; commit top-left r4c3 and bottom-right r8c3 (5x1, area 5).
Step 11: Anchor r7c4=7; commit top-left r4c4 and bottom-right r10c4 (7x1, area 7).
Step 12: Anchor r5c1=8; commit top-left r1c1 and bottom-right r8c1 (8x1, area 8).
Step 13: Anchor r7c2=5; commit top-left r4c2 and bottom-right r8c2 (5x1, area 5).
Step 14: Anchor r2c3=9; commit top-left r1c2 and bottom-right r3c4 (3x3, area 9).
Step 15: Finish the lower-left redraw with anchor r9c2=4; commit top-left r9c2 and bottom-right r10c3 (2x2, area 4).
Step 16: Anchor r10c1=2; commit top-left r9c1 and bottom-right r10c1 (2x1, area 2).

Colors in this level:

Yellow, Violet, Cyan, Blue, Green, Red, Pink, Purple, Orange, Mint, Lavender, Teal, Coral, Indigo, Gold, Lilac

Do not keep the temporary r9c1:r9c3 strip; it steals the lower-left cell needed by r10c1=2.
Do not split r1c5:r10c5. The area-10 clue at r6c5 is a single ten-cell vertical rectangle.
Do not make r9c2=4 a horizontal four-cell bar; its final footprint is the 2x2 block r9c2:r10c3.

Start with the three-cell bottom and right-edge strips while the lower-right corner is open.
Reserve column 5 from r1 through r10 for r6c5=10.
Finish the lower-left 2 and 4 as separate rectangles, not a provisional horizontal strip.

Board notes 5 details

Layout: Full 10-row by 9-column board with 90 playable cells. Clues: r2c3=9, r2c6=3, r2c9=3, r3c7=6, r5c1=8, r5c9=6, r6c3=5, r6c5=10, r6c6=7, r6c8=3, r7c2=5, r7c4=7, r8c8=9, r9c2=4, r10c1=2, and r10c8=3.
Goal: Partition all 90 cells into sixteen rectangles: the final bounds are r1c1:r8c1, r1c2:r3c4, r1c5:r10c5, r1c6:r3c6, r1c7:r3c8, r1c9:r3c9, r4c2:r8c2, r4c3:r8c3, r4c4:r10c4, r4c6:r10c6, r4c7:r5c9, r6c7:r6c9, r7c7:r9c9, r9c1:r10c1, r9c2:r10c3, and r10c7:r10c9.
Opening: The source first commits r10c8=3 as r10c7:r10c9, r8c8=9 as r7c7:r9c9, and r6c8=3 as r6c7:r6c9, then fixes the long column bars before closing the left and top regions.
Danger Zone: The temporary r9c1:r9c3 lower-left strip is not final. Preserve r9c1:r10c1 for r10c1=2 and r9c2:r10c3 for r9c2=4, and never break the r1c5:r10c5 area-10 bar.
Mechanics: This 10x9 board is a long-bar partition: the area-10 column and two area-7 columns leave narrow corridors. The video visibly redraws the lower-left preview before victory.

What is the long rectangle for r6c5=10?
It is the full column-5 strip r1c5:r10c5, a 10x1 rectangle.
How should the lower-left corner finish?
Use r9c1:r10c1 for the 2 clue and r9c2:r10c3 for the 4 clue.
How many rectangles solve Level 32?
The solved 10x9 board contains sixteen persistent rectangles covering all 90 cells.