Install deepin-icon-theme by entering the following commands in the terminal:
sudo apt update sudo apt install deepin-icon-theme
Icon Theme for Deepin software and Deepin Desktop Environment
Deepin Icon Theme is the default icon theme for DDE, based on Papirus icon theme. This package contains: * Deepin Icon Theme * Sea Icon Theme * Deepin Cursor Theme . This package is part of DDE (Deepin Desktop Environment).