I've somehow managed to have all tabs show up as the control character
^I in VIm, specifically gvim 8.1.1 on Windows 10.
All I have related to tabs in vimrc is this:
I do also have these lines that point to something else, so to speak, but wouldn't expect them to have an influence on tabs showing as control characters:
source $VIMRUNTIME/mswin.vim set nocompatible behave mswin
" highlight tabs and trailing spaces "set listchars=trail:- "set list