The Files paragraph uses a reference to a license which is only defined in the Header paragraph. The copyright specification requires that the Files paragraph either contains the full license itself or references a "stand-alone" License paragraph, and not the Header paragraph.
For more information please consult:
The tag is present in Lintian version
That is the most recent version we know about.
We use semantic versions.
The patch number is a commit step indicator relative to the
release tag in our Git
You can find the detection logic for this version at commit ffc17eb. For merge requests, please use the latest version in the Lintian check debian/copyright/dep5.