Endermen pathfinding looks for the simplest path rather than the optimal path.

Endermen pathfinding in 1.13 is slightly different than in 1.12.2 where they look for the simplest path that will get them close to the endermite instead of the optimal path that will get them closest to the endermite like in 1.12.2. There are some cases where this change has caused problems. For instance, with a certain enderman farm design (shown in the video) that works perfectly in 1.12.2 but stops working properly in 1.13 due to the pathfinding change.

Video showing this bug (endermen): https://www.youtube.com/watch?v=6bPVEC38N9M