When working with a Debian Linux Desktop it is ideal to install the 'vim-gtk3' package instead of the 'vim' package because the first includes the 'copy to clipboard' feature. The 'vim' package left out this feature on purpose to be used on servers, because most servers do not use a GUI.
You may test your current VIM version and clipboard feature with the following command:
vim --version | grep clipboard
The output of this command should be '+clipboard'. This shows your VIM version supports clipboard access. If not, it will show '-clipboard'.
To install vim-gtk3 instead of vim, first remove vim and then install vim-gtk.
sudo apt remove vim; sudo apt install vim-gtk3;