Okay, now what the heck?
Now my C Drive on my computer says: 581 GB capacity, 238 free.
It just added my 70 some GB back!
This is good, of course, but -why-?
Even Sequoia is showing it proper now! See below.
This corresponds much more closely now to my highlighted C drive, too: 581 - 343 = 269. There is still some discrepancy, but it is only 30 gigs, rather than a lot more.
Still what is wrong with this?
[recovering disk space - old attachment deleted by admin]