No sources except FC include accidentals before the 8th quaver in the bar; FC features 
's restoring e
-e1, written most probably in pencil. As was the case with a number of other similar additions, those accidentals were added by H. Scholtz, who introduced them also into the 1879 Peters edition he edited. An analogous change can also be found in many other subsequent editions of the Preludes. A possible oversight of the flats restoring e-e1 would not be unusual here, since similar mistakes are among the most frequently committed by Chopin; however, the very possibility of a mistake does not mean that the mistake was actually committed, particularly since there are no musical reasons to consider the version written in the sources to be erroneous.
Compare the passage in the sources»
category imprint: Interpretations within context
issues: Omissions to cancel alteration, Foreign hand additions in manuscripts
notation: Pitch