“…Recently, it was conjectured by El Abdalaoui-Shparlinski-Steiner [10] that Kloosterman sums should in general not correlate with low-complexity sequences. Whilst this was shown to be true for (vertical) averages over the entries of the Kloosterman sums, see [24,Example 10.4] or [10,Theorem 2.8], it is wide open for (horizontal) averages over the modulus in this generality. In this paper, we make progress towards this conjecture by completely resolving the case of periodic functions.…”