  In 1998, Wang constructed an ergodic action of the compact quantum group
$U_n^+$ (free unitary quantum group) on the Cuntz algebra $\mathcal{O}_n$.
Later, in 2018-2019, S. Joardar and A. Mandal showed that the quantum
automorphism group of the Cuntz algebra $\mathcal{O}_{n}$ (as a graph
$C^*$-algebra) is $U_n^+$ in the category introduced by them.
  In this article, we explore the quantum symmetry of the direct sum of Cuntz
algebras viewing them as a graph $C^*$-algebra in the category as mentioned
before.
  It has been shown that the quantum automorphism group of the direct sum of
non-isomorphic Cuntz algebras $\{\mathcal{O}_{n_i}\}_{i=1}^{m}$ is
${U}_{n_1}^{+}*{U}_{n_2}^{+}* \cdots *{U}_{n_m}^{+}$ for distinct $n_i$'s, i.e.
if $ L_{n_i}$ (the graph contains $n_i$ loops based at a single vertex) is the
underlying graph of $\mathcal{O}_{n_i}$, then
  \begin{equation*}
  Q_{\tau}^{Lin}(\sqcup_{i=1}^{m} ~ L_{n_i}) \cong *_{i=1}^{m} ~~
Q_{\tau}^{Lin}(L_{n_i}) \cong {U}_{n_1}^{+}*{U}_{n_2}^{+}* \cdots
*{U}_{n_m}^{+}.
  \end{equation*}
  Moreover, the quantum symmetry of the direct sum of $m$ copies of isomorphic
Cuntz algebra $\mathcal{O}_n$ (whose underlying graph is $L_n$) is $U_n^+ \wr_*
S_m^+,$ i.e.
  \begin{equation*}
  Q_{\tau}^{Lin}(\sqcup_{i=1}^{m} ~ L_n) \cong Q_{\tau}^{Lin}(L_n) \wr_* S_m^+
\cong U_n^+ \wr_* S_m^+.
  \end{equation*}
  On the other hand, it is known that the quantum automorphism group of $m$
disjoint copies of a simple, connected graph $\Gamma$ is isomorphic to the free
wreath product of the quantum automorphism group of $\Gamma$ with $S_m^+$.
Though an analoguous result is true for $\mathcal{O}_{n}$ (as a graph
$C^*$-algebra), we have provided a counter-example to show that this result is
not in general true for an arbitrary graph $C^*$-algebra.
