Fixing incorrect colors in Vim when running inside tmux

Incorrect colours within Vim is quite a common problem. An example of such:

working-normal
broken-tmux

If $TERM is set correctly for tmux (screen-256color), adding a TC flag to term env to enable true color display:

set-option -sa terminal-overrides ",xterm*:Tc"
set-option -sa terminal-overrides ",screen*:Tc"

working-tmux