Endermen picking up blocks don't count towards the mob cap, and don't despawn, potentially cluttering up the world with endermen if they cannot place the block down

Endermen picking up blocks don't count towards the mob cap, and don't despawn, potentially cluttering up the world with endermen if they cannot place the block down. This can especially be observed in warped forests, as well as in a custom setups in an area with blocks endermen cannot replace (like item frames).

To reproduce, set the world border to 128, go into the Nether, reach the ceiling, place tnt floating 1 block above the bedrock (so endermen can't walk on top of it), and spawn endermen. When the endermen pick up the tnt, they will be stuck forever. (note: the world border only serves to confine the endermen within an observable area; it still works without the world border)