The ftplugin for the make filetype includes setlocal noexpandtab, which should take precedence over what's in your vimrc.

  % vim Makefile
  :verbose set expandtab?
  noexpandtab
    Last set from /usr/share/vim/vim90/ftplugin/make.vim line 15
  
  % vim file.c
  :verbose set expandtab?
  noexpandtab
    Last set from ~/.vim/vimrc line 56

but I think that may not work as intended for OP as they don't have "filetype on plugin".