The tag is present in Lintian version 2.109.24. That is the most recent version we know about.
The first line of the changelog entry for this package appears to indicate it is a non-maintainer upload (by including either that string or the string "NMU" and not saying that it's an acknowledgement), but the changelog indicates the person making this release is one of the maintainers.
If this was intended to be an NMU, do not add yourself as a maintainer or uploader. Otherwise, please rephrase your changelog entry to not cause confusion.