Why I am having these discontinue lines in the table created with latex for PDF documents?

Hi dear community,

I have created a table in a PDF document using latex in R markdown, but I am having the issue that the table has discontinued lines that make this table not look good, I do not understand why and I have not been able to find an answer on internet. I am putting part of the code that I am using:

header-includes: 
   \usepackage{lastpage}
   \usepackage{fancyhdr}
   \usepackage{datetime}
   \pagestyle{fancy}
   \fancyhf{}
   \setlength\headheight{30pt}
   \addtolength{\topmargin}{20pt}
   \lhead{\includegraphics[width=3cm, height=3cm]{Pfizer_Logo.jpg}}
   \renewcommand{\headrulewidth}{0pt}
   \cfoot{Pfizer, Confidential}

output:
  pdf_document:
    citation_package: natbib
    keep_tex: yes
    fig_caption: yes
    fig_width: 3
    latex_engine: pdflatex
    df_print: kable

table_cat_vals %>%
  left_join(age_cats) %>%
  select(var_label, label2, label, case_number, percentage) %>%
  group_by(var_label) %>%
  kbl(booktabs = T, format = "latex", longtable = T, align = c("l", "l", "l", "r", "r"), escape=F, col.names = c("","","", "Number of cases", "Percentage (\\%)")) %>%
  collapse_rows(columns = 1:2, row_group_label_position = 'stack', latex_hline = 'full', longtable_clean_cut = F) %>%
column_spec(column = 3, width = c("3.8in")) %>%
  row_spec(0, bold = T, color = "white", background = "#051391")

Thank you very much for your help.