If one has them in the first place or is able to catch them before they're wiped..
Indeed i'm starting to suspect (as you alluded to in another thread) this is NOT DJI Go 4 specific afterall.
I also checked an IOS backup of my iPad prior to manually syncing and no *FLY*DAT files were created/made there either. Curiously, i did see a file named ".DJIFlightRecordDeletListeba05eb517375032" (the dot usually significes it's a hidden file), it's contents was just an ASCII single-line CSV-type file of .txt files (no line terminator either).
The mystery of the empty MCDatFlightRecords drectory/missing App-.DAT files continues... :-/
Just to clarify - DJI GO 4 and DJI Fly apps both create DAT files as described here, in the apps MCDatFlightRecords directory. The Fly app DAT files are deleted under iOS and Android when the flight records are synchronized with DJI, either with manual or auto-sync. The GO 4 app files are deleted on manual sync (there is no auto-sync) under iOS, but not under Android when I last checked.