Which aligns with what I said. 500MB is most of 700MB. The difference is made up of other various hardware reservations.

My completely standard Windows 11 install says 64GB installed and 63.9 GB usable. I can assure you that doesn't mean Windows is only using 100MB.

Go to task manager and look for "Hardware Reserved" at the bottom right of the memory tab. I bet you'll see a number very close to 700MB. Mine says 87MB.