\begin{table}
\centering
\begin{tblr}[         %% tabularray outer open
]                     %% tabularray outer close
{                     %% tabularray inner open
colspec={Q[]Q[]Q[]Q[]},
hline{2}={1-2}{solid, black, 0.03em},
hline{3}={2,4}{solid, black, 0.03em, l=-0.5},
hline{2}={3}{solid, black, 0.03em, r=-0.5},
hline{3}={3}{solid, black, 0.03em, r=-0.5},
hline{4}={1-4}{solid, black, 0.05em},
hline{1}={1-4}{solid, black, 0.08em},
hline{5}={1-4}{solid, black, 0.08em},
cell{1-2}{3}={}{halign=c},
cell{1-2}{4}={}{halign=c},
cell{1}{1}={c=3}{halign=c},
cell{1}{2}={}{halign=c},
cell{2}{1}={}{halign=c},
cell{2}{2}={c=2}{halign=c},
}                     %% tabularray inner close
A &  &  &  \\
& B &  & D \\
C & C &   & E \\
1 & 2 & 3 & 4 \\
\end{tblr}
\end{table} 
