A git package is sometimes based on a specific snapshot of the code from a point in time. Its can be newer, but its not a guarantee of it being newer simply because it has git in the name.
In this case the git package is older. Its best to look at the Last Updated date on the AUR page to see if its newer.
So theoretically, even if the PKGBUILD itself is not “updated”, this particular one should pull in the latest version of epub2txt.
The one caveat is that you will not be notified of upstream updates, and will have to manually force the PKGBUILD to build again when you discover a new version was released by the upstream developers.
EDIT: Just saw that @Yochanan summarized it more succinctly in the post above.
The search above will show the two packages. Notice the text for one is red. If you select one, notice the options in the upper right hand side (i.e., PKGBUILD, FLAGGED).
Just in case:
Use the AUR at your own risk!
No support will be provided by the Manjaro team for any issues that may arise relating to software installations from the AUR. When Manjaro is updated, AUR packages might stop working. This is not a Manjaro issue Arch User Repository - Manjaro