This is an auto-filed bug because net-misc/remmina installs .desktop files that do not pass validation. The issue was originally discovered on amd64, but it may be reproducible on other arches as well. If you think that a different summary clarifies the issue better, feel free to change it. Attached build log and emerge --info.
Created attachment 640198 [details] build.log build log and emerge --info
Reported upstream & fixed w/ sed in the ebuild for now, thanks