A 
under the 2nd quaver is both in A1 and GE1, which proves that it is not an inaccuracy, but a precise indication on how to preserve the G1 bass note with a pure G major chord. In the remaining sources, the mark was moved due to carelessness or due to an attempt at correcting the allegedly inaccurate notation of A1: in FE (→EE) it was moved under the 3rd beat of the bar, whereas in GE2 to the beginning of the bar.
Compare the passage in the sources »
category imprint: Differences between sources
issues: Inaccuracies in FE, GE revisions
notation: Pedalling