add custom latex header with include in header

Hello, sorry to bother again, I'm trying to add some custom header options to produce pdf using crossref, I'm currently using the crossref pandoc-crossref v0.3.16.0 git commit UNKNOWN (UNKNOWN) built with Pandoc v3.1.2, pandoc-types v1.23 and GHC 9.0.2

pandoc 3.1.2 Features: +server +lua

And I'm trying to add some header options, the following command to run it is as follows: pandoc demo.md -o demopdf.pdf -d encabezadoapa.yml

And the yaml file is the following:

metadata:
  bibliography: biblio.bib
  link-citations: true
  figureTitle: "Figura"
  tableTitle: "Tabla"
  figPrefix: "Figura "
  eqnPrefix: "Ecuación "
  tblPrefix: "Tabla "
  loftitle: "# Lista de figuras"
  lotTitle: "# Lista de tablas"
  header-includes: 
    - "\\usepackage{fancyhdr}"
    - "\\newcommand{\\pcdoc}{Pandoc-crossref documentation}"
toc: true
toc-depth: 3
filters:
  - parse-latex.lua
  - pandoc-crossref
  - citeproc
reference-doc: custom-referencestyles.docx
pdf-engine: xelatex

Everything works well without the header, but I need it to add some options inside the pdf output, and it does not make any difference when I put the command indicated in the manual at the beggining or in the very end, deleting the header it works well, the error obtained is this:

Error producing PDF.
! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.104 \textbackslash

Do I forgot something to add or am I configuring in the wrong way?

lierdakil / pandoc-crossref

add custom latex header with include in header #390