Chopin did not pay special attention to cautionary flats before the e1 and g1 notes in bars 21 and 23. The first was written only in AIII, it was also added in GE2op (→#GE3op) and EEW1 (→EEW2). The second is present in the majority of the sources – it was overlooked only in AII and GE2Db (→GE3Db→GE4Db).
Compare the passage in the sources »
category imprint: Differences between sources; Corrections & alterations
issues: EE revisions, Chopin's hesitations, Errors in GE, GE revisions, Cautionary accidentals
notation: Pitch