Because it's a retroreflective patch. The reflection will be orders of magnitude more intense than a diffuse reflection from a white surface.
We are talking about the height of the black tape. This is more accurately measured here as 1.17m, but you claimed 1.35
Meaning your laser is pointing down.
By analyzing the video. Did you not see the images in the post you quoted?
I don't see your point here. What is the green line supposed to be?
How can you comare two imaginary points?
Where is the black tape?