Nextcloud desktop client, integration in file manager

I am running F34 with MATE desktop. I also run the Nextcloud desktop client to sync directories into my own cloud. Week ago I implemented that the ‘places’ port of a filemanager also displays separately the directories to be synched, see example the column on the left side with the nextcloud icons:

But now I would like to turn this off. I can not remember what causes those particular ‘nextcloud to by synced directories’ to be displayed in that particular window. This happens not in case I open my file manager (caja) directly, but when I access directories indirectly, e.g. when downloading from internet and selecting a place where to store the download or when I write a mail and would like to add attachments.
Any idea how this interface to nextcloud has been implemented? Any plugin that can be turned off? I already checked my repository for any nextcloud add-ons that I possibly installed in the past but did not find how I activated this display and how I could deactivate.

Thank you in advance