The software center of Linux Mint 20.1 Cinnamon Edge offers Viber as a flatpak package. Installation is a breeze and the only downside is that it takes a lot more space than the .deb version from the official Viber homepage. I'm not sure if it is a common problem, but for me, the indicator icon was missing from the cinnamon taskbar.
Disable ads in Viber on Windows
Out of nowhere, Viber started displaying ads at the bottom of the contact list of the Viber window. I understand that Viber must make a living, but in my case the ads covered one third of the contact list and this really frustrated me. Luckily it turns out you can disable these ads without any side effects...