the save file format is terrible. i lose track of my files all the time because moving 4k videos between different devices shifts the created date. got damn.

Because of this, I personally make my folder names mm_dd_yyyy_description_of_area and dump the contents of my SD into it.

You blame DJI because you can't use a PC or remember where you put a file,

This is not  DJI issue all digital cameras that i have used have always saved this way without the DJI prefix
As above strip card to one folder, go into folder and use the rename feature .... Bingo call them what you want!

If you copy/paste, it will change the date created as it's actually creating a different file.What you will find is that the date modified doesn't change (unless you actually modify the file).
So, two semi-useful options are to cut/paste the files or just use the date modified and understand that you'll have to subtract the length of the video from that time.

It would be best if DJI would change the filename structure to something based on the date/time that the file is created (YYYYMMDD-HHMMSS or similar).

Of course, pictures should contain a date taken attribute (too bad videos don't).
JJ