The tag is present in Lintian version 2.104.328. That is the most recent version we know about.
The watch file specifies an upstream version number which matches
the upstream portion of an old
debian/changelog entry, and the
debian/changelog entry specifies a newer upstream
version. The version number in the watch file is very likely to be
incorrect and probably should be replaced with the current expected
upstream version. Otherwise, DEHS and similar projects will think the
package is out of date even when it may not be.