I compared it with another L5. The icon which is labeled Contacts Importer went away. Why?
Update:
There are two files in /usr/share/applications/ which smell as related:
purism@pureos:~$ egrep 'Icon|Exec' /usr/share/applications/l5-contacts-*
/usr/share/applications/l5-contacts-exporter.desktop:Icon=mail-folder-outbox-symbolic
/usr/share/applications/l5-contacts-exporter.desktop:Exec=/usr/bin/l5-contacts-exporter %U
/usr/share/applications/l5-contacts-importer.desktop:Icon=preferences-desktop-personal
/usr/share/applications/l5-contacts-importer.desktop:Exec=/usr/bin/l5-contacts-importer %U
purism@pureos:~$ /usr/bin/l5-contacts-exporter -h
Usage: /usr/bin/l5-contacts-exporter [--vcf|--csv], or just press the contacts exporter Icon in the app tray
But the icon is not on the screen: This issue is more an academic one, bacause I do not need neither the icon nor the software in this case 