The dim. indication was added by Chopin in GC (→GE), most probably also in the base text to EE. Its absence in FE proves that Chopin probably omitted the base text to this edition at the time of completing the Stichvorlage manuscripts in these bars. Similarly in bar 8.
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category imprint: Differences between sources; Corrections & alterations
issues: EE revisions, GE revisions, Authentic corrections in GC
notation: Verbal indications