In C++ Insights - Episode 1: The invisible things there is an example:
struct A {};
struct B {
explicit operator A() { return {}; }
};
void DangerousFunc(const A&) {}
int main()
{
DangerousFunc(static_cast<A>(B{}));
}
The transformation that C++ Insights shows leads to:
DangerousFunc(static_cast<A>(static_cast<A>(B{}.operator A())));
which is incorrect. The first static_cast<A> is missing const.
It was initially reported by @peterkochlarsen and @DanielKhoshnoud.