The best reason I can think of is that the behind the scenes OS must require FAT32 for the USB file system. Because of that, most OS cannot format an external USB drive in the FAT32 format that is larger than 32GB. If you want to use a larger USB stick, you will have to use a regular computer and format it there, either with powershell command line utilities, or a 3rd party downloaded GUI application. I can’t say that even if you have a larger drive formatted FAT32, that the system would recognize it.
As far as the 2.5hr recording limit, also is related to the FAT32 file system, maximum single file size allowed is 4GB. Also don’t forget that you can only record 2 channels/outputs at a time to USB.
