how to avoid this change of size in tikz-cd

Question

I was happy to learn here how to place "pullback-corner" decorations in tikz-cd squares using labels instead of phantom diagonals, but now I noticed that the label technique seems to affect the dimensions of the diagram. The code

\documentclass{article}
\usepackage{tikz-cd,amssymb}
\begin{document}
[
\begin{tikzcd}
U\cap V \ar[r] \ar[d] & V \ar[d] \
U \ar[r] & |[label={[label distance=-3mm]135:\ulcorner}]| P
\end{tikzcd}
\quad
\begin{tikzcd}
U\cap V \ar[r] \ar[d] & V \ar[d] \
U \ar[r] & P 
\end{tikzcd}
\quad
\begin{tikzcd}
U\cap V \ar[r] \ar[d] & V \ar[d] \
U \ar[r] & P \ar[ul, phantom,"\ulcorner",pos=0]
\end{tikzcd}
]
\end{document}

produces the following diagram:

The left square, using label, is larger than the middle square without decoration, and the right square with the decoration placed on a phantom diagonal.

Is there a way to avoid this resizing?