The tag is present in Lintian version 2.104.328. That is the most recent version we know about.
This file is in a location generally used for detached debugging
symbols, but it appears to contain a complete copy of the executable or
library instead of only the debugging symbols. Files in subdirectories
/usr/lib/debug mirroring the main file system should contain
only debugging information generated by
--only-keep-debug. Binaries or shared objects built with extra
debugging should be installed directly in
/usr/lib/debug or in
subdirectories corresponding to the package, not in the directories that
mirror the main file system.
If you are using dh_strip with the --dbg-package flag, don't also install
the library in
/usr/lib/debug. dh_strip does all the work for
Please refer to Debian Developer's Reference section 6.7.9 for details.