Minecraft v1.16.5
Forge v36.1.16
Better End v1.6.0
Pokecube AIO v3.12.0a

I have discovered that structures from Better End are generating in the Distorted World Dimension from the Pokecube AIO mod, which uses the datapack system to create it's dimensions. Maybe a dimension blacklist for structures could be added? The biome from this dimension is also pulled and added to the End in the BetterEnd config, which I had to manually disable.