Neovim tabstops and git diff

I am new to vim and have difficulty setting it up. I am working with a FRR code in which the tab is 8 spaces. I want to see 4 spaces instead of 8 and have added the following settings [*options.lua*]: vim.opt.expandtab = true vim.opt.shiftwidth = 4 vim.opt.tabstop = 4 vim.opt.smarttab = true vim.opt.autoindent = true vim.opt.smartindent = true git shows new lines in the file as: - memset(&mroute, 0, sizeof(mroute)); + memset(&mroute, 0, sizeof(mroute)); stream_get(&mroute.sg.src, client->ibuf, 4); stream_get(&mroute.sg.grp, client->ibuf, 4); I don't see the difference in the file itself, but git shows that it is there. How can this be fixed?