Endermen are able to pick up nylium and the new nether plants. Then they go off and die with it or whatever endermen like to do in their freetime. This results in nylium slowly being removed from warped forests. It makes it difficult to build in this biome, because the endermen keep stealing all the ground blocks. A possible solution would maybe be to have them spawn with nylium or plants, but not be able to actually pick up or set down the block.