A
compare
b. 66-69
The four-bar slur in the left hand part was added in the proofing of FE (→EE). This is almost certainly one of the elements introduced by Chopin in order to make the notation more precise.
Compare the passage in the sources »
category imprint: Differences between sources; Corrections & alterations
issues: Accompaniment changes, Authentic corrections of FE
notation: Slurs