In a peer-reviewed publication, one of the length-contraction effects of a physical object, depicted in the diagram, is used to derive conclusions. It has been referenced by other authors and in Wikipedia. The paper is not identified here intentionally, hopefully, to avoid bias in possible explanations.
Edit summary: The original diagram is modified in response to initial comments, to clarify that what was referred to as 'changes in the y-direction' is not relevant to the main question. Please ignore the ‘old set of drawings’ and kindly consider the same question with reference to the ‘new set of drawings”, as edited.
Question: Which of the bottom two diagrams in the edited drawing above shows (descriptively) the effect of length contraction for an object depicted with solid lines in the top diagram?
The old diagram is included below, for reference with the initial comments.