custom_hlgroups is flaky

[Huluk]

return {
  {
    "ofirgall/ofirkai.nvim",
    enabled = true,
    lazy = false,
    priority = 1000,
    config = function()
      vim.cmd [[colorscheme ofirkai]]
      require('ofirkai').setup {
        custom_hlgroups = {
          TabLineSel = { fg = "#f20aee", bg = "#343942" },
          TabLine = { fg = "#78b6e8", bg = "#343942" },
        },
      }
    end,
  },
}

Sometimes when I start vim (nvim -p a b to see tabs), only one of the overrides takes effect, sometimes both work and I get the correct layout. It seems truly random, and happens with a minimal config (just the lazy.nvim setup code and this one plugin).
When only one override works, it's always "TabLineSel", for whatever reason.

Aside: It's also weird that vim.cmd [[colorscheme ofirkai]] resets the colors to defaults, when most of the time I would want to do the setup once, then switch freely between themes.