What sort of file is this, from its file name. I guess dblock, but please confirm.
“10,857.98 TiB reduction” is discussed in below. Its fix seems in today’s Beta.
Because it seems to be a bad report, jumping into Beta might not be worth it.
I’m not sure if it relates to the too-small-looking dlist. Might be a different bug.
Developer might have an opinion. I see other oddly small ones in the reports.
Possibly it’s a benign mis-report, but I have no other opinion on it beyond this.