Weird inverse color for some faces

_Originally posted by @dungnq271 in https://github.com/dracula/emacs/issues/59#issuecomment-1718738200_

Hi I accidentally `(set-face-background 'default "#2" nil )` and the background worked.
But in a tmux session I don't know why some of the words are highlighted in blue. The colours work ok outside tmux.

Reproduce the reported face-color behavior in Emacs inside a tmux session, comparing it with the same configuration outside tmux. Start with the reported `set-face-background` expression and the Dracula theme configuration; done means the affected words no longer appear blue in tmux while the colors remain correct outside it.

Written by the indexing model from the issue text.