Verify flathub app
The app https://flathub.org/apps/com.adrienplazas.Metronome is not shown as verified at Flathub. The process is rather simple, just log in at flathub.org with your github account that maintains the flatpak manifest and your account at gitlab.gnome.org that appears in the Doap file and you can verify the app there. Please drop by the Flathub room at matrix if you have any questions.