Explain the problem.
Assume the following documents:

• sample.md:

  ---
  bibliography: sample.bib
  ---
  
  We all love @BenjaminHornigold [pages 1-10].
  Wait, I mean @BenjaminHornigold [page 1-10].
  Wait, I mean @BenjaminHornigold [p.\ 1-10].
  Wait, I mean @BenjaminHornigold [poop deck 1-10].
  What about @BenjaminHornigold [on pages 1-10]?

• sample.bib:

  @book{BenjaminHornigold,
    author = {Benjamin Hornigold},
    title  = {A proof of Pirate ipsum},
    year   = {1680},
  }

Running the following command:

pandoc --citeproc sample.md -o sample.tex

Gives the following output:

We all love Hornigold (1680, 1--10). Wait, I mean Hornigold (1680,
1--10). Wait, I mean Hornigold (1680, 1--10). Wait, I mean Hornigold
(1680, poop deck 1-10). Wait, I mean Hornigold (1680, on pages 1-10).

\phantomsection\label{refs}
\begin{CSLReferences}{1}{0}
\bibitem[\citeproctext]{ref-BenjaminHornigold}
Hornigold, Benjamin. 1680. \emph{A Proof of Pirate Ipsum}.

\end{CSLReferences}

Citeproc swallows the prefixes pages, page, and p. in a manner that has to be intentional, but is, to the best of my reseasch, undocumented.

Pandoc version?
Running Pandoc 3.1.12.3 on macOS 13.

pandoc 3.1.12.3
Features: +server +lua
Scripting engine: Lua 5.4
User data directory: /Users/keri/.local/share/pandoc
Copyright (C) 2006-2023 John MacFarlane. Web: https://pandoc.org
This is free software; see the source for copying conditions. There is no
warranty, not even for merchantability or fitness for a particular purpose.