Lerp odd behavior with Math.random

The green and blue planes both have some random value applied to each of their vertices z components. I’m lerpin the green plane towards the grey plane that works fine. but the issue is I can’t lerp the green towards the blue. If I remove the randomness from the blue plane the lerping works. Frustrating, What’s going on and how do I solve this? why can’t things go smoothly persevere lol

Here is a working example