Steps to reproduce

1. Build a 2-block high dirt pillar on level ground.
2. 2 blocks from the pillar, place 4 spruce saplings.
3. Bonemeal the NW sapling to grow a giant spruce tree.
4. Remove the spruce tree.
5. Place 4 spruce saplings in the same spots as step (2).
6. Bonemeal the NW sapling.

Expected result

A giant spruce tree grows.

Actual result

A giant spruce tree does not grow. The top dirt block from step (1) turns into podzol in step (3), and the podzol then blocks the growth of the tree in step (6).
Podzol blocks giant spruce growth.mp4

Podzol spreads to dirt blocks then cant grow another tree if podzol is in the 6x6 area around a 2x2 spruce tree