The dynamic indications of the final part of the Etude were almost certainly added by Chopin to the three, generally finished, Stichvorlage manuscripts. In bars 28-31, EE1 transferred the most elaborately developed version with 
in bar 28 and diminuendo in bars 30-31, A (→GE) includes only , while FE, devoid of indications, remained in the shape preceding the additions. Circa 10 years after the publication of the Etudes, Chopin added here 
in a pupil's copy (FED), which, according to us, is to be considered as an alternative dynamic concept and not a conclusive change.
Deletion of in EE2 (→EE3) is most probably related to the addition of fingering after FE.
Compare the passage in the sources»
category imprint: Differences between sources; Corrections & alterations
issues: Annotations in teaching copies, Annotations in FED, Authentic post-publication changes and variants
notation: Verbal indications