macOS Sonoma 14.5, Zsh 5.9

I have a PDF files that is 4.85 × 7.84 inches. When I insert a blank page with

pdfcpu pages insert -p 2 -m after input.pdf output.pdf

the blank page doesn't respect the dimensions of the document and is 8.5 × 11 inches instead.

• Is it a bug?

• or is this behavior by design and should be worked around somehow? I tried

  pdfcpu pages insert -p 3 -m after resize -u in 'dim:4.85 7.84' input.pdf output.pdf
  

  but this produces an error.