As in b. 252, Chopin deleted in A the 
marking placed between the staves and put it before the chords on the bottom stave. The change was not included by FE (→GE,EE); moreover, EE added another mark before the L.H. part.
Compare the passage in the sources »
category imprint: Differences between sources; Corrections & alterations; Source & stylistic information
issues: EE revisions, Inaccuracies in FE, Deletions in A
notation: Verbal indications