1.17
After testing a lot i found a solution for the problem,
for people how have the same error i will explain here how the Layer System from vanilla works in 1.17
itrm: in the run method (of the transformer)
this was a bug in my code but I just had to ignore the y value in BiomeSource#getNoiseBiome
AreaTransformer0: can be used as base biome "layer", the parameters are: the LazyAreaContext, x pos in the area, y (z) pos in the area
AreaTransformer1: transformer to add a biome "layer" to an existing AreaFactory, the parameters are: the LazyAreaContext, the Area which is create from the AreaFactory itrm
the x pos in the area, y (z) pos in the area
AreaTransformer2: transformer to combine two AreaFactory for example the current BiomeLayer and a ClimateLayer, the parameters are: the LazyAreaContext, the Area which in create from the first AreaFactory itrm, the Area which is create from the second AreaFactory itrm, the x pos in the area, y (z) pos in the area
BishopTransformer: transformer to add a biome "layer" to an existing AreaFactory with a bit more logic, the parameters are: the LazyAreaContext, the biome id north west from the AreaFactory itrm, the biome id north east from the AreaFactory itrm, the biome id south east from the AreaFactory itrm, the biome id south west from the AreaFactory itrm, the center biome id from the AreaFactory itrm
C0Transformer: can also be used as base biome "layer", the parameters are: the LazyAreaContext, biome id of the x and y (z) pos in the area with offset 0
C1Transformer: can also be used as base biome "layer", the parameters are: the LazyAreaContext, biome id of the x and y (z) pos in the area with offset 1 in x+/y+
CastleTransformer: transformer to add a biome "layer" to an existing AreaFactory with a bit more logic, the parameters are: the LazyAreaContext, the biome id north from the AreaFactory itrm, the biome id east from the AreaFactory itrm, the biome id south from the AreaFactory itrm, the biome id west from the AreaFactory itrm, the center biome id from the AreaFactory itrm
very simple zooms the Area so biomes are larger
this was an error in my Layer, because i used the wrong transformer, and i used BigContext#nextRandom to get the biome
is a simple long value, you can choose a random one or you use scheme like 1, 2, 3, 4, ...
note if you use a value twice it could lead problems (particularly if you used the same Layer)
vanilla has only the system which is explained above and forge has unfortunately nothing
I hope my explanation was helpful, if something is wrong let me know this and i will edit the post
i will create soon a Example Mod about the Biome generation and the different Layers and possible implementations, when the mod is finished i will edit this post and add the link to the repo
-> since Minecraft change the Biome generation, I won't publish an Example Mod for the 1.17 anymore, i will wait till the final release for 1.18.x