The traces of corrections visible in FE prove the Chopinesque proofreading of slurring. The removed slurs were shorter and, as it seems, incomplete – they encompassed, consecutively, 2 beats of bar 291, entire bar 292 and 2 beats of bar 293. Over the last beat of bar 293, there was the beginning of the slur continued in bar 294 (on a new line). It is difficult to evaluate whether these were corrections of mistakes and inaccuracies of the engraver or changes to the authentic, original slurring (perhaps both). There is a similar situation in bars 307-308.
Compare the passage in the sources»
category imprint: Corrections & alterations; Source & stylistic information
issues: Authentic corrections of FE
notation: Slurs