\begin{table}
\centering
\begin{talltblr}[         %% tabularray outer open
entry=none,label=none,
note{}={\emph{Source}: Simulated data.},
]                     %% tabularray outer close
{                     %% tabularray inner open
colspec={Q[]Q[]Q[]},
hline{2}={1-3}{solid, black, 0.05em},
hline{1}={1-3}{solid, black, 0.08em},
hline{9}={1-3}{solid, black, 0.08em},
cell{2,5}{1}={c=3}{},
}                     %% tabularray inner close
A / B & B / C & C / D \\
↓ & ↓ & ↓ \\
-0.655 & 1.54 & -0.51 \\
-0.498 & -0.11 & -0.48 \\
↑ & ↑ & ↑ \\
0.332 & 0.24 & 0.76 \\
1.121 & -0.17 & 0.79 \\
-0.064 & 0.58 & 1.74 \\
\end{talltblr}
\end{table} 
