Like this?

- simpler, far more concise table code can be obtained by use of the
longtblr
of tabularray
package
- table is huge, so you may consider to reduce page borders that table would have more space and in it can be use bigger font size, for example
\footnotesize
\documentclass[11pt]{report}
\usepackage[margin=25mm]{geometry} % or other suitable page layout
\usepackage[export]{adjustbox}
\usepackage{enumitem}
\usepackage{rotating}
\usepackage{makecell}
\usepackage{tabularray}
\UseTblrLibrary{siunitx,
varwidth}
\usepackage{pdflscape}
\begin{document}
\begin{landscape}
\begingroup
\setlist[enumerate]{nosep,
itemsep=0.5ex,
leftmargin=*}
\settowidth\rotheadsize{Transportation} % from makecell
\setkeys{Gin}{width=\linewidth}
\begin{longtblr}[
caption = {Table with transformation details},
label = {appendix:tableindicators}
]{hlines, vlines,
colsep = 4pt,
colspec = {c X[1.3, c, m]
X[1.5, c, m] X[2,l, m]
Q[c,m, mode=math]
Q[c,m]
Q[c, si={table-format=-1.3}]
Q[c, si={table-format= 2.3}]
X[2,c]
},
measure = vbox,
rows = {font=\footnotesize},
row{1} = {guard, font=\scriptsize\bfseries, c, mode=text},
cell{even[2]}{2-5,Z} = {r=2}{},
vspan = even,
stretch = -1,
rowhead = 1,
}
% columns headers
Theme & Indicator
& Method of Calculation
& Transformation
& Polarity
& Type
& Skewness
& Kurtosis
& Distributions \\
% table body
\SetCell[r=8]{c, cmd=\rothead} Transportation
& Train Station
& Walking distance to nearest
& \begin{enumerate}
\item Natural Logarithm(x)
\item Winsorisation(6, 11)
\end{enumerate}
& - & Raw Data
& 2.397
& 10.552
& \includegraphics{example-image-duck}
\\
& & & & & Transformed
& -0.528
& 2.469
& \\
& Bus Stop
& Walking distance to nearest
& \begin{enumerate}
\item Winsorize(0, 1000)
\end{enumerate}
& - & Raw Data
& 3.871
& 37.268
& \includegraphics{example-image-duck}
\\
& & & & & Transformed
& -1.189
& 4.368
& \\
& Bus Stop with Frequent Services
& Walking distance to nearest
& \begin{enumerate}
\item Winsorize(0, 3500)
\end{enumerate}
& - & Raw Data
& 2.817
& 15.448
& \includegraphics{example-image-duck}
\\
& & & & & Transformed
& -1.682
& 5.843
& \\
& Bikeability
& Total length of bikeable paths/roads, divided by area
& \begin{enumerate}
\item Box-Cox ($\lambda=-2$)
\item Winsorisation(-50, -25)
\end{enumerate}
& + & Raw Data
& 1.560
& 7.246
& \includegraphics{example-image-duck}
\\
& & & & & Transformed
& 0.576
& 3.431
& \\
\end{longtblr}
\endgroup
\end{landscape}
\end{document}
Addendum:
Regarding your comment you should be aware, that table can breaks only between rows. This means, that in in your case you can have a problems with handling of multirow cells:
- For correct table breaking between multirow cells try to terminate rows with inserted images with
\\*
. It prevent table break after this row.
- You may consider to turn first column into row with table parts "subtitles".
- It may also helped to reduce for a wee bit of images heights.
An example of such table redesign is:

\documentclass[11pt]{report}
\usepackage[margin=25mm]{geometry} % or other suitable page layout
\usepackage[export]{adjustbox}
\usepackage{enumitem}
\usepackage{xcolor}
\usepackage{tabularray}
\UseTblrLibrary{booktabs,
siunitx,
varwidth}
\NewTableCommand\subtitle{%
\SetCell[r=2, c=8]{l, m, bg=gray!10,
font=\large\bfseries\itshape,
cmd=\rule[-1ex]{0pt}{4ex}
}
}
\usepackage{pdflscape}
\begin{document}
\begin{landscape}
\small
\setlist[enumerate]{nosep,
itemsep=0.5ex,
leftmargin=*}
\setkeys{Gin}{width=\linewidth, height=17mm}
\begin{longtblr}[
caption = {Table with transformation details},
label = {appendix:tableindicators}
]{hline{even[3]} = {dashed},
hline{Z} = {solid, \heavyrulewidth},
colsep = 4pt,
colspec = {@{}
X[1.3, l, m]
X[1.6, c, m]
X[2,l, m]
Q[c,m, mode=math, font=\Large]
Q[c]
Q[c, si={table-format=-1.3}]
Q[c, si={table-format= 2.3}]
X[2,c]
@{} },
measure = vbox,
rowsep = 3pt,
row{1} = {guard, font=\footnotesize\bfseries, c, mode=text},
cell{even[2]}{1-4,Z} = {r=2}{},
vspan = even,
stretch = -1,
rowhead = 1,
}
% columns headers
\toprule
Indicator
& Method of Calculation
& Transformation
& Polarity
& Type
& Skewness
& Kurtosis
& Distributions \\
% table body
\midrule
\subtitle Theme: Transportation
& & & & & & & \\*
& & & & & & & \\
Train Station
& Walking distance to nearest
& \begin{enumerate}
\item Natural Logarithm(x)
\item Winsorisation(6, 11)
\end{enumerate}
& - & Raw Data
& 2.397
& 10.552
& \includegraphics{example-image-duck}
\\*
& & & & Transformed
& -0.528
& 2.469
& \\
Bus Stop
& Walking distance to nearest
& \begin{enumerate}
\item Winsorize(0, 1000)
\end{enumerate}
& - & Raw Data
& 3.871
& 37.268
& \includegraphics{example-image-duck}
\\
& & & & Transformed
& -1.189
& 4.368
& \\
Bus Stop with Frequent Services
& Walking distance to nearest
& \begin{enumerate}
\item Winsorize(0, 3500)
\end{enumerate}
& - & Raw Data
& 2.817
& 15.448
& \includegraphics{example-image-duck}
\\
& & & & Transformed
& -1.682
& 5.843
& \\
Bikeability
& Total length of bikeable paths/roads, divided by area
& \begin{enumerate}
\item Box-Cox ($\lambda=-2$)
\item Winsorisation(-50, -25)
\end{enumerate}
& + & Raw Data
& 1.560
& 7.246
& \includegraphics{example-image-duck}
\\
& & & & Transformed
& 0.576
& 3.431
& \\
bla bla bla
& Total length of bikeable paths/roads, divided by area
& \begin{enumerate}
\item Box-Cox ($\lambda=-2$)
\item Winsorisation(-50, -25)
\end{enumerate}
& + & Raw Data
& 1.560
& 7.246
& \includegraphics{example-image-duck}
\\
& & & & Transformed
& 0.576
& 3.431
& \\
\subtitle Theme: Other transportation
& & & & & & & \\
& & & & & & & \\
Uber
& Total length of bikeable paths/roads, divided by area
& \begin{enumerate}
\item Box-Cox ($\lambda=-2$)
\item Winsorisation(-50, -25)
\end{enumerate}
& + & Raw Data
& 1.560
& 7.246
& \includegraphics{example-image-duck}
\\*
& & & & Transformed
& 0.576
& 3.431
& \\
Car Sharing
& Total length of bikeable paths/roads, divided by area
& \begin{enumerate}
\item Box-Cox ($\lambda=-2$)
\item Winsorisation(-50, -25)
\end{enumerate}
& + & Raw Data
& 1.560
& 7.246
& \includegraphics{example-image-duck}
\\*
& & & & Transformed
& 0.576
& 3.431
& \\
Bike Sharing
& Total length of bikeable paths/roads, divided by area
& \begin{enumerate}
\item Box-Cox ($\lambda=-2$)
\item Winsorisation(-50, -25)
\end{enumerate}
& + & Raw Data
& 1.560
& 7.246
& \includegraphics{example-image-duck}
\\*
& & & & Transformed
& 0.576
& 3.431
& \\
% \bottomrule
\end{longtblr}
\end{landscape}
\end{document}
\documentclass
and end with\end{document}
, a Minimal Working Example (MWE) please. It makes copy and pasting easier when the code can be compiled and also we do not need to guess what commands or packages you are using. Also, we do not have access to your images you are including