Gerbv has Categories=Application;Electronics;Engineering;, which is not valid. See http://standards.freedesktop.org/menu-spec/latest/apa.html 'Application' is not a valid category. The other two are fine, but are 'additional' categories. A main category from the top list is required, though none are a perfect fit. I'd suggest 'Office', or maybe 'Development' or 'Utility' (tho 'Utility' doesn't really seem to fit based on the description).
Seeing a relating sed line in the ebuild: Please use the desktop-file-validator from dev-util/desktop-file-utils, create a patch, use and send it upstream, so this stuff gets actually fixed, instead resorting to sed. Polluting our ebuilds using sed, when not needed is not pleasant for us, as we never get to know, when a sed line is superfluous, nor does it match the Gentoo Social Contract, not to report such issues back to upstream.
stable 2.4.0 has only Categories=Engineering;Electronics; While that shows up nicely if you have sci-electronics/electronics-menu installed, desktop-file-validate complains about a missing main category.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=b87b002a4c0ebb5997e477a07f876c808391f3aa commit b87b002a4c0ebb5997e477a07f876c808391f3aa Author: David Seifert <soap@gentoo.org> AuthorDate: 2020-02-10 10:00:16 +0000 Commit: David Seifert <soap@gentoo.org> CommitDate: 2020-02-10 10:00:16 +0000 sci-electronics/gerbv: Remove old Closes: https://bugs.gentoo.org/220421 Package-Manager: Portage-2.3.88, Repoman-2.3.20 Signed-off-by: David Seifert <soap@gentoo.org> sci-electronics/gerbv/Manifest | 2 - sci-electronics/gerbv/files/gerbv-2.6.1-ru.patch | 12 ----- sci-electronics/gerbv/gerbv-2.6.0.ebuild | 54 ------------------- sci-electronics/gerbv/gerbv-2.6.1.ebuild | 67 ------------------------ 4 files changed, 135 deletions(-)