Forests don't spawn trees near the positive edges, but overstretch bounds on the negative edges

Forests (includes, forest, taiga, birch forest) are biased against spawning trees near the positive X and Z edges of the biome, while it does not hesitate to spawn trees beyond its edges in the negative X and Z edges.
This effect also applies to (suspected) all decorations, as seen in flowers in flower forests.

 

Positive Edge Examples:

1        860 100 730

1        1470 100 70

 

Negative Edge Examples:

-2116075216570249986 -310 100 -539

 

-8754354938067898153    3800 100 5100

 

I must also mention that 1.12 and earlier seems to have issues with trees overstepping bounds in the negative directions, although it does not get as extreme as in 1.13.