KindleTool v1.6.5?
https://www.mobileread.com/forums/sh...d.php?t=225030
The version number does not get bump'd until the snapshot becomes the release.
Until then, versions newer than the last release (v1.6.4 for example) are marked by a sequential snapshot id to show how much newer the snapshot is than the most recent release.
(And for people who have trouble with <version>-<snapshot id>, there is also a build date included - five weeks ago is as recent as you get right now - unless you clone the public repo and build it yourself).
That is just the way the author does such things.
(things can become a bit arbitrary in an all volunteer project)