It's not hyperbole. I make a backup of my computer, with the output being a bunch of 500MB files. And I would then copy or move those files into a folder on the file stream drive. It's not entirely consistent, and it used to do less, but with some update it decided that it should upload way too many files at once. I've had to switch to an entirely different program to upload those files sequentially.

What is the program that you are using? I am currently using odrive for macOS since they don't have DriveFS support for Apple Silicon. odrive work ok, it just have a weird file conflict sometime.

I'm using rclone to do big uploads.

I still use DriveFS for everything else, at least for now. Rclone is capable of mounting the drive but it's not really designed for that.