I think the original intent was to increase file sizes, to keep file count below 5000. At 5000 files (perhaps enough for 100 GB of source), something bad happens, described as “I cannot access the directory anymore”. I wonder if this is a Microsoft destination that’s showing the infamous 5000 item list view limit as discussed in ‘No files were found at the remote location’ using Onedrive for business and possibly fixed in the Graph backends (a.k.a. “v2”) that should be moved to anyway?
@Bjoern what Destination Storage Type is breaking at 5000 files? Can you change that access method to v2? You’ll probably need to set up a new AuthID, but maybe the 5000 limit will go away (based on testing link above).