The tag is present in Lintian version 2.104.234. That is the most recent version we know about.
This package appears to be covered by the GNU GPL but depends on the OpenSSL libssl package and does not mention a license exemption or exception for OpenSSL in its copyright file. The GPL (including version 3) is incompatible with some terms of the OpenSSL license, and therefore Debian does not allow GPL-licensed code linked with OpenSSL libraries unless there is a license exception explicitly permitting this.
If only the Debian packaging, or some other part of the package not linked with OpenSSL, is covered by the GNU GPL, please add a Lintian override for this tag. Lintian currently has no good way of distinguishing between that case and problematic packages.
Refer to Bug#972181 and http://meetbot.debian.net/debian-ftp/2020/debian-ftp.2020-03-13-20.02.html for details.
This is a classification. There is no issue with your package.