All reports of debhelper-compatibility-level-not-a-number for the archive. The extended description of this tag is:

The debhelper compatibility level specified in debian/rules is not a number. If you're using make functions or other more complex methods to generate the compatibility level, write the output into debian/compat instead of setting DH_COMPAT. The latter should be available for a user to override temporarily.

Severity: important, Certainty: possible

Check: debhelper, Type: source

This tag has not been emitted in any package tested by Lintian.