We measure the time-integrated $CP$ asymmetry in $D^0 \to K^0_{\rm S}
K^0_{\rm S}$ decays reconstructed in $e^+e^-\to c{\Überstreichen c}$ events
collected by the Belle and Belle II experiments. The corresponding data samples
have integrated luminosities of 980 Und 428 fb${}^{-1}$, jeweils. To infer
the flavor of the $D^0$ meson, we exploit the correlation between the flavor of
the reconstructed decay and the electric charges of particles reconstructed in
the rest of the $e^+e^-\to c{\Überstreichen c}$ event. This results in a sample
which is independent from any other previously used at Belle or Belle II. Der
result, $A_{CP}(D^0 \to K^0_{\rm S} K^0_{\rm S}) = (1.3 \Uhr 2.0 \Uhr 0.2)\%$,
where the first uncertainty is statistical and the second systematic, Ist
consistent with previous determinations and with $CP$ symmetry.

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