End terrain generation always places biomes in the whole chunk

Confirmed for 1.13.1.

Works normally in 1.16 - there can be multiple biomes in a chunk.

Cannot reproduce in 1.17.1.

I have confirmed this bug is still present in the current version (25w05a) but the description should be updated. I attached an image of a map I built of the biomes in the end. Here, redstone blocks are built on the end_midlands biome, emerald blocks are built on the small_end_islands biome, diamond blocks are built on the end_barrens biome, and gold blocks are built on the end_highlands biome. I added glass above on the chunk boundaries. This map shows one particular y slice, the biomes also vary in the y direction along the border.

The map shows that the biomes continue to fall within chunk boundaries. However, now it is the case that the biomes can be blended over the boundary by 1 to 2 blocks. Testing older versions revealed that this started to happen in 19w36a (1.15 snapshot). The bug should be updated to say that the biomes are not strictly within a chunk boundary anymore but can blend up to two blocks into another chunk. Otherwise, the biomes do still follow a chunk based pattern unlike biomes in the overworld and nether that allows blobby biomes independent of chunks.