I try to install viber via command :
$ flatpak install flathub com.viber.Viber
the result is :
$ Error: Wrong size for extra data https://download.cdn.viber.com/cdn/desktop/Linux/viber.deb
error: Failed to install com.viber.Viber: Wrong size for extra data https://download.cdn.viber.com/cdn/desktop/Linux/viber.deb