The second column of the table becomes narrower when I add extra rows, how can I solve this?

Question

I would like to add extra rows, because this is a long table. But the second column of the table becomes narrower when I add extra rows.

Here is the code, the last several rows are in %comment mode, because when I decomment them, the table column 2 becomes very narrow:

\documentclass{report}
\usepackage[utf8]{inputenc}
\usepackage{graphicx} % Required for inserting images
\usepackage{setspace}% for\doublespacing
\usepackage{indentfirst}% for indent the first line
\usepackage{longtable}
\usepackage{textalpha}
\usepackage{ragged2e}
 \usepackage[T1]{fontenc} % <-- new
\usepackage{xltabular} 
\usepackage{amsmath}
\usepackage{caption}
\DeclareUnicodeCharacter{2212}{-}%new
\begin{document}
\section{DUSP genes expression in non-brain tissues in animal and human}
\newcolumntype{L}{>{\RaggedRight}X} % suspend full justification
% special new column type for header row:
\newcolumntype{C}{>{\centering\arraybackslash}%
    p{\dimexpr\textwidth-2\tabcolsep-2\arrayrulewidth\relax}}
\begin{xltabular}{\textwidth}{ | l | L | c | l | l | } % <-- new
%% headers and footers
\caption{DUSP genes expression in non-brain tissues in animal and human\label{long5}}\
\hline
\multicolumn{5}{ | C | }{DUSP genes expression in non-brain tissues in animal and human}\
\hline
Protein & Tissue/ Cell line & Species & Protein/ mRNA & Ref. \
\hline
\endfirsthead
\hline
\multicolumn{5}{|c|}{Continuation of Table \ref{long5}}\
\hline
Protein & Tissue/ Cell line & Species & Protein/ mRNA & Ref. \
\hline
\endhead
\hline
\endfoot
\hline
\multicolumn{5}{| c |}{End of Table}\
\hline\hline
\endlastfoot
SSH1 & PC-3 Cell & Human & Protein & \cite{Ottman2016TheCancer} \
     & Aortas&  Mice   & Protein  &   \cite{Yamashiro2015AbnormalMice}  \
     &   Keratinocytes& Human&Protein& \cite{Kligys2007TheKeratinocytes}  \
SSH2 &   Carcinoma cell lines& Human&  Protein/mRNA&  \cite{Lu2014KnockdownFLCN}\
     & Vascular smooth muscle cell& Rat&    mRNA& \cite{Torres2011SlingshotFormation}\
  &    PC12 Cell&   Human&  Protein & \cite{Xu2015GPCR-mediatedChemotaxis}\
  & CD4+ T cells    &Human  &Protein&   \cite{Kanai2014IdentificationCells}\
  & Keratinocytes & Human   &Protein&   \cite{Kligys2007TheKeratinocytes}\
SSH3& Colorectal cancer&    Human&  Protein/mRNA&   \cite{Hu2019SSH3LIMK1/Rac1}\
    & Prostate cancer&  Human&  Protein & \cite{Muller2018ProteomicMetastases} \
   &  Blood&    Human&  mRNA&   \cite{Wang2020IdentificationDisease}\
PRL1  &  Liver, Intestine & Mice &  Protein/mRNA &  \cite{Diamond1996ExpressionIntestine}\
     & Mid guts&    Drosophila  &mRNA&  \cite{Lin2013ExpressionZebrafish}\
&amp; Testis&amp;   Mice&amp;   Protein&amp; \cite{Bai2016RoleSpermatogenesis}\\

&amp;  Prostate&amp;    Human&amp;  mRNA&amp; \cite{Shinmei2014IdentificationMethod} \\

 &amp; Ovarian cancer&amp;  Human&amp;  Protein/mRNA&amp;   \cite{Reich2011ExpressionCarcinoma}\\


PRL2 & Lung cancer& Human   &Protein/mRNA&  \cite{Wang2012Metastasis-associatedInvasion}\
&amp;    Ovarian cancer&amp;    Human   &amp;Protein/mRNA&amp;  \cite{Reich2011ExpressionCarcinoma}\\

&amp;    Testis &amp; Mice&amp; Protein &amp;  \cite{Bai2016RoleSpermatogenesis}\\

 &amp;  Thymocyte &amp;     Mice&amp;   mRNA    &amp;  \cite{Kobayashi2017ProteinProgenitors} \\

&amp;    Skeletal muscle &amp;  Mice&amp;   Protein/mRNA&amp;\cite{Dong2012PhosphataseProtein,Zeng1998MousePRL-1}\\ 

PRL3 &amp;   Colon cancer&amp;   Mice/Human&amp;    Protein/mRNA&amp;\cite{Li2005GenerationMetastases,Zimmerman2013TargetedCancer} \\

     &amp;    Prostate cancer &amp;  Human&amp;  Protein/mRNA   &amp;  \cite{Vandsemb2016PhosphataseMigration}\\

     &amp;  Ocular melanoma cells&amp;      Human&amp;      Protein&amp;  \cite{Foy2017PRL-3/PTP4A3Cells}\\

     &amp;  Breast cancer&amp;      Human&amp;      Protein/mRNA&amp;  \cite{Patel2015RoleCarcinoma}\\

     &amp;  Skeletal muscle, heart&amp;     Human&amp;      mRNA&amp;  \cite{Matter2001RoleSignaling}\\

     &amp;  Skeletal muscle, heart&amp;     Mice&amp;   mRNA&amp;  \cite{Zeng1998MousePRL-1}\\

CDC14A &amp; Brain vascular endothelial cell&amp;   Human &amp; Protein &amp;\cite{Su2015HCdc14AHypoxia}\\

&amp;Oocytes &amp;  Mice&amp;   Protein&amp;    \cite{Schindler2009TheMouse}\\

&amp;Gastric tissue &amp;   Human&amp;  mRNA    &amp; \cite{Song2010MutationalInstability}\\

&amp;HeLa cells&amp;    Human&amp;  Protein &amp; \cite{Mailand2002DeregulatedSegregation}\\

&amp;Lymph nodes, liver, colon, kidneys, testis &amp; Human&amp;Protein&amp; \*\cite{Uhlen2015Proteomics.Proteome}\\


CDC14B &  HeLa cells&   Human&  Protein & \cite{Wu2008Cdc14BDuplication} \
&amp; Bone Osteosarcoma Epithelial Cells (U2OS Line) &amp;  Human&amp;  Protein &amp; \cite{Cho2005TheMicrotubules}\\

&amp; Lymph nodes, liver, colon, kidneys, testis &amp;  Human&amp;  Protein&amp;   \cite{Uhlen2015Proteomics.Proteome} *\ \\

&amp; Oocytes&amp;      Mice&amp;   Protein/mRNA &amp; \cite{Schindler2009TheMouse} \\


CDC14C  &  Vulva precursors & C. elegans &  Protein &   \cite{Roy2011ControlElegans}\
 &amp; Mononuclear cells &amp;  Human &amp;     mRNA     &amp; \cite{Szmit2010GeneFailure}\\


PTENs &   Endometrial cancer&   Human&      Protein&  \cite{Mutter2000AlteredPrecancers}    \
&amp;  Pancreas&amp;    Human&amp;      Protein/mRNA&amp;   \cite{Ebert2000OverexpressionCancer}\\

&amp;   Colorectal cancer&amp;      Human&amp;      Protein&amp;  \cite{Frattini2007PTENPatients}   \\

&amp;  Cochlear lateral wall&amp;   Mice&amp;   Protein&amp;  \cite{Dong2014TheWall}\\

&amp;  Uterus&amp;      Mice&amp;   Protein&amp;    \cite{Lague2010DecidualMouse}\\

&amp;  Ovary cells&amp;     Chinese hamster&amp;    Protein &amp;  \cite{Kerr2006PTENGSK-3}\\


% Myotubularins& Lungs, muscles& Mice&  Protein& \cite{Uhlen2015Proteomics.Proteome} * \
%             &endocrine tissue &       &         &            \
%             & bone marrow&       &         &            \
%             & liver&       &         &            \
%            & immune system&       &         &            \
%            &gallbladder&       &         &            \
%             &pancreas&       &         &            \
%   &Skin&  Human&  mRNA&   \cite{Raess2017WANTEDFamily}\
%         &lungs&       &         &            \
%         &vagina&       &         &            \
%   &Lungs& Human&  Protein&    \cite{Uhlen2015Proteomics.Proteome} * \
%         &muscles&         &       &      \
%          & endocrine tissue&       &         &            \
%          & bone marrow&       &         &            \
%          & immune system&       &         &            \
%          & liver &       &         &            \
%         & pancreas&       &         &            \
%          &  gallbladder&       &         &            \
\end{xltabular}
% This is footnote
\begin{minipage}{10cm}
\small Note:* (www.proteinatlas.org)\ BNST:The bed nucleus of the stria terminalis 
\end{minipage}
\end{document}

Normal width of the column2:

Narrowed column 2: