Install cinnamon-screensaver-webkit-plugin by entering the following commands in the terminal:
sudo apt update sudo apt install cinnamon-screensaver-webkit-plugin
Webkit plugin for cinnamon-screensaver
cinnamon-screensaver is a screen saver and locker that aims to have simple, sane and secure defaults, and be well integrated with the Cinnamon desktop. . This package contains the plugin for using webkit screensavers.