20Mb missing after format

I have a Cruzer labeled as “high-speed” 2.0. When formatted, there’s 20-30 Mb unaccounted for… i.e. when unallocated, drive “claims” 7.45Gb. When formatted, that changes to 7.42Gb. When you “open” it, there’s nothing–no files, etc. When I put (or tried) to an Linux O.S. on it, for whatever reason it 'split" to 3 partitions??? That wasn’t the doings of the “bootable drive” installer!!!  I checked the drive and formatted w/ Aomei partition assitant and it showed 7.44Gb of 7.45Gb with fat32 format. Windows won’t “read” it??? Checked the drive and reported all sectors OK and a healthy partition??? What would that 10-20 or 30 Mb be and how do I remove whatever it is? Oh…what exactly is a “high speed” 2.0…the dongle is red not black like other 2.0 drives. Yes, I know, 3.0 is blue dongle.

TNX;

Rick

This may help.

https://petapixel.com/2012/10/10/why-hard-drives-and-memory-cards-have-less-space-than-advertised/