I've got the same problem as of this morning. I don't even qualify for the bronze 'long-distance cacher' badge and it has it listed as diamond.
Furthest cache 93432 km away, which is in space, I'm fairly sure I've never been there.
I checked the GC page for my furthest find, and the co-ords etc have not changed.
Would love a fix for this.
Update for 1/18/20: The bug is no longer affecting my BadgeGen stats and badges, but my furthest find is now listed incorrectly as a different cache, and the distance is still way over what it should be, but by less of a margin than yesterday.
Update for 1/20/20 Bug still happening. no change from the previous update, furthest cache is still an incorrect GC, and the distance is like 7000 ish kms away, when it should be in the double digits.