Pdf output contains '.' instead of e.g., "Disclaimer"

I am using a copernicus article:

---
title: Template for preparing your manuscript submission to Copernicus journals using RMarkdown
journal: "`r rticles::copernicus_journal_abbreviations(journal_name = 'communication')`"
author:
  - given_name: Daniel
    surname: Nüst
    affiliation: "1, *"
    email: daniel.nuest@uni-muenster.de
    corresponding: true
  - given_name: Josiah
    surname: Carberry
    affiliation: 2
    email: j.carberry@orcid.org
  - given_name: Markus
    surname: Konkol
    affiliation: "1, *"
  - given_name: Nikolaus
    surname: Copernicus
    # authors can have multiple affiliations, which can also be used to mark deceased coauthors
    affiliation: "3, †"
# If you have more than one corresponding author, add them manually using the following structure (note the commas):
# Two authors: Daniel Nüst (daniel.nuest@uni-muenster.de) and Josiah Carberry (j.carberry@orcid.org)
# Three authors or more: Daniel Nüst (daniel.nuest@uni-muenster.de), Josiah Carberry (j.carberry@orcid.org), and Markus Konkol (m.konkol@wwu.de)
# If the following line is uncommented, the "corresponding: true" above are ignored
#correspongdingauthors: Daniel Nüst (daniel.nuest@uni-muenster.de) and Josiah Carberry (j.carberry@orcid.org)
# If an author is deceased, please mark the respective author name(s) with a dagger '†' and add a further affiliation; put the decease date in the 'address' field", see 'Nikolaus Copernicus' in template.
# If authors contributed equally, please mark the respective author names with an asterisk '*' and add a further affiliation: 'These authors contributed equally to this work.'", see template.
affiliation:
  - code: 1
    address: Institute for Geoinformatics, University of Münster, 48149 Münster, Germany
  - code: 2
    address: Psychoceramics, Wesleyan University, Middletown, CT, United States
  - code: 3
    address: University of Ferrara, Ferrara, Italy
  - code: "†"
    address: deceased, 24 May 1543
  - code: "*"
    address: These authors contributed equally to this work.
abstract: |
  The abstract goes here.
  It can also be on _multiple lines_.
bibliography: sample.bib
running:
  title: R Markdown Template for Copernicus
  author: Nüst et al.
# This section is mandatory even if you declare that no competing interests are present.
competinginterests: |
  The authors declare no competing interests.
# See https://publications.copernicus.org/for_authors/licence_and_copyright.html, normally used for transferring the copyright, if needed. 
# Note: additional copyright statements for affiliated software or data need to be placed in the data availability section. 
copyrightstatement: |
  The author's copyright for this publication is transferred to institution/company. 
### The following commands are for the statements about the availability of data sets and/or software code corresponding to the manuscript.
### It is strongly recommended to make use of these sections in case data sets and/or software code have been part of your research the article is based on.
### Note: unless stated otherwise, software and data affiliated with the manuscript are assumed to be published under the same licence as the article (currently Creative Commons 4.0)
availability:
  #code: |
  #  use this to add a statement when having only software code available
  #data: |
  #  use this to add a statement when having only data sets available
  codedata: |
    use this to add a statement when having data sets and software code available
  sample: |
    use this section when having geoscientific samples available
videosupplement: |
  use this section when having video supplements available
authorcontribution: |
  Daniel wrote the package. Josiah thought about poterry. Markus filled in for a second author.
disclaimer: |
  We like Copernicus.
acknowledgements: |
  Thanks to the rticles contributors!
appendix: |
  \section{Figures and tables in appendices}
  Regarding figures and tables in appendices, the following two options are possible depending on your general handling of figures and tables in the manuscript environment:
  \subsection{Option 1}
  If you sorted all figures and tables into the sections of the text, please also sort the appendix figures and appendix tables into the respective appendix sections.
  They will be correctly named automatically.
  \subsection{Option 2}
  If you put all figures after the reference list, please insert appendix tables and figures after the normal tables and figures.
  
  To rename them correctly to A1, A2, etc., please add the following commands in front of them:
  `\appendixfigures` needs to be added in front of appendix figures
  `\appendixtables` needs to be added in front of appendix tables
  
  Please add `\clearpage` between each table and/or figure. Further guidelines on figures and tables can be found below.
output:
  rticles::copernicus_article: 
    highlight: NULL
    keep_tex: true
  bookdown::pdf_book:
    base_format: rticles::copernicus_article # for using bookdown features like \@ref()
---

\introduction[Introduction]

Introduction text goes here.

When I render, I get:

Why do I have these unexpecred '.'s?

> xfun::session_info('rticles')
R version 4.5.2 (2025-10-31)
Platform: aarch64-apple-darwin20
Running under: macOS Tahoe 26.2, RStudio 2026.1.0.392

Locale: en_US.UTF-8 / en_US.UTF-8 / en_US.UTF-8 / C / en_US.UTF-8 / en_US.UTF-8

Package version:
  base64enc_0.1.3   bslib_0.10.0      cachem_1.1.0      cli_3.6.5         digest_0.6.39     evaluate_1.0.5    fastmap_1.2.0    
  fontawesome_0.5.3 fs_1.6.6          graphics_4.5.2    grDevices_4.5.2   highr_0.11        htmltools_0.5.9   jquerylib_0.1.4  
  jsonlite_2.0.0    knitr_1.51        lifecycle_1.0.5   memoise_2.0.1     methods_4.5.2     mime_0.13         R6_2.6.1         
  rappdirs_0.3.4    rlang_1.1.7       rmarkdown_2.30    rticles_0.27.12   sass_0.4.10       stats_4.5.2       tinytex_0.58     
  tools_4.5.2       utils_4.5.2       xfun_0.56         yaml_2.3.12      

Start by rendering the supplied Copernicus R Markdown template with the reported rticles session information and inspect the generated PDF around the disclaimer and other statement sections. Trace which template or rendering entry point produces the unexpected periods, then verify that the intended labels and text render without them.