The tag is present in Lintian version 2.108.13. That is the most recent version we know about.
Upstream metadata is stored under an obsolete path.
Upstream MEtadata GAthered with YAml (UMEGAYA) is an effort to collect
meta-information about upstream projects from any source package
with a publicly accessible VCS via a file called
Older versions of this specification used
as meta-information storage file.
You should move any such file to