The notation of the slur in bar 20 in A must be considered as inaccurate – the slur is most probably broken (perhaps there was no more ink in the quill). This shortening was not included already in GE. In the remaining sources, the entire bar is provided with a separate slur.
From bar 20, CDP is written by another hand, considering performance indications (at least some of them). Taking this into account, we already include the versions of this source in the notes concerning performance indications. In this case, in the copied manuscript there were most probably two whole-bar slurs.
Compare the passage in the sources»
category imprint: Differences between sources; Source & stylistic information
issues:
notation: Slurs