What happens if you run Kosaraju’s algorithm on a DAG?
We should think about the property of SCC(strongly connected component)

A directed graph $G(V, E)$ is acyclic if and only if $G$ has no SCCs with more that one vertex. Because a directed cycle is SCC by definition of the cycle.

Hence, the result of the Kosaraju’s algorithm on a DAG will return $|V|$ trivial SCCs. In other words, it returns $\{\{v\}\mid v\in V\}$.