Two-by-two arrangements of spruce saplings convert more blocks in the south and east directions into podzol

When 2x2 Spruce Saplings grow and attempt to replace the lower dirt-like blocks into Podzol, there is an additional row of blocks replaced in the east and south directions.

Step to reproduce

1. Repeatly grow Spruce Trees in same position (Clean leaves and logs if necessary).

2. Observe the horizontal reach of Podzols in four directions.

Expected Result

There are 5 blocks of Podzols reaching out in all four directions.

Actual Result

There are 5 blocks of Podzols reaching out in North and West directions, but 6 in South and East directions.

Possible Cause

When growing, all of the 4 saplings place alter_ground decorator below themselves, instead of only the one in NW direciton.