will it be a bug for adding task to queue by other thread ?

[Frandy]

When add task into queue, it call execute as below,

template <std::invocable F> void execute(F &&f) {
        std::size_t i = count++ % _deques.size();

        _in_flight.fetch_add(1, std::memory_order_relaxed);
        _deques[i].tasks.emplace(std::forward<F>(f));
        _deques[i].sem.release();
    }

Since it use lock free deque, it supposes only one thread can push and pop at the front, and other threads only steal at the bottom. Is it right?
If so, it may have problem as adding task to thread i by other thread.
Would you please help explain why it is ok ?

Best wishes, thanks.