I finally can solve it.
Just overwrite a few icons located at /usr/share/icons/Ambiant-MATE/status/22 , the icons installed by Ubuntu Mate 20.04.1 seems to be damaged. The icons are at attachment file.
You must do it as root.
I finally can solve it.
Just overwrite a few icons located at /usr/share/ icons/Ambiant- MATE/status/ 22 , the icons installed by Ubuntu Mate 20.04.1 seems to be damaged. The icons are at attachment file.
You must do it as root.