Neovim Lualine Winbar Coloring is incorrect on startup

Upon startup, the right separator of my winbar in lualine is colored incorrectly (note the darker background on the right):

But after sourcing my lualine config file, it looks how it should:

My lualine config is already required upon startup, so I have no idea what is causing this issue. Here's my config:

local theme = vim.g.colors_name
local lualine = require('lualine')
local function window()
    return vim.api.nvim_win_get_number(0)
end -- test

local gruvbox_colors = {
    fg     = '#ebdbb2',
    fg2    = '#a89984',
    bg     = '#282828',
    bg2    = '#3c3836',
    black  = '#282828',
    red    = '#fb4934',
    green  = '#b8bb26',
    blue   = '#83a598',
    yellow = '#fe8019',
}

local tokyodark_colors = {
    fg     = "#a0a8cd",
    bg     = "#111219",
    bg2    = "#1a1b27",
    fg2    = "#4a5057",
    black  = "#06080a",
    red    = "#ee6d85",
    yellow = "#d7a65f",
    green  = "#95c561",
    blue   = "#7199ee",
}

local minimal_colors = {
    fg     = '#DFE0EA',
    fg2    = '#6e7380',
    bg     = '#191b20',
    bg2    = '#21252d',
    black  = '#16181d',
    red    = '#E85A84',
    green  = '#94DD8E',
    blue   = '#7eb7e6',
    yellow = '#E9D26C',
}

local kanagawa_colors = {
    fg     = '#DCD7BA',
    fg2    = '#727169',
    bg     = '#1f1f28',
    bg2    = '#2a2a37',
    black  = '#16161d',
    green  = '#98bb6c',
    yellow = '#ffa066', -- yellow/orange
    red    = '#ff5d62',
    blue   = '#7E9Cd8',
}

-- Required colors in theme:
-- fg := lighter text color
-- fg2 := darker text color
-- bg := center color
-- bg2 := different background color
-- black := darkest color for foreground of highlighted text
-- green, yellow, red, blue := colors from palette

-- local _colors = {
--     fg     = '',
--     fg2    = '',
--     bg     = '',
--     bg2    = '',
--     black  = '',
--     green  = '',
--     yellow = '', -- yellow/orange
--     red    = '',
--     blue   = '',
-- }


local colors = {}
if theme == "gruvbox" then
    colors = gruvbox_colors
elseif theme == "tokyodark" then
    colors = tokyodark_colors
elseif theme == "minimal" then
    colors = minimal_colors
elseif theme == "kanagawa" then
    colors = kanagawa_colors
else
    colors = tokyodark_colors
end

local THEME = {
    normal  = {
        a = { fg = colors.black, bg = colors.green, gui = "bold" },
        b = { fg = colors.fg, bg = colors.bg2 },
        c = { fg = colors.fg2, bg = colors.bg },
        x = { fg = colors.fg2, bg = colors.bg },
        y = { fg = colors.fg, bg = colors.bg2 },
        z = { fg = colors.fg, bg = colors.bg2 },
    },
    visual  = { a = { fg = colors.black, bg = colors.yellow, gui = "bold" } },
    replace = { a = { fg = colors.black, bg = colors.red, gui = "bold" } },
    insert  = { a = { fg = colors.black, bg = colors.blue, gui = "bold" } },
    command = { a = { fg = colors.black, bg = colors.green, gui = "bold" } },
}

local config = {
    options = {
        icons_enabled = true,
        theme = THEME,
        component_separators = { left = '', right = '' },
        section_separators = { left = '', right = '' },
        -- '' '' '' ''
        disabled_filetypes = {
            statusline = {
                'NvimTree',
                'alpha'
            },
            winbar = {
                'NvimTree',
                'alpha'
            },
            NvimTree = {},
        },
        ignore_focus = {},
        always_divide_middle = true,
        globalstatus = true,
        refresh = {
            statusline = 1000,
            tabline = 1000,
            winbar = 1000,
        },
    },

    sections = {
        lualine_a = { 'mode' },
        lualine_b = {}, --{ 'branch', 'diff', 'diagnostics', }
        lualine_c = { 'filename' },
        lualine_x = { require('auto-session-library').current_session_name, },
        lualine_y = { 'fileformat', 'filetype', },
        lualine_z = { 'os.date("%H:%M")' },
    },
    tabline = {},
    winbar = {
        lualine_a = {},
        lualine_b = {},
        lualine_c = {},
        lualine_x = {},
        lualine_y = {
            {
                'filename',
                separator = { left = ' ', right = ' ' },
            }
        },
        lualine_z = {},
    },
    inactive_winbar = {
        lualine_a = {},
        lualine_b = {},
        lualine_c = {},
        lualine_x = {},
        lualine_y = {
            {
                'filename',
                separator = { left = ' ', right = ' ' },
            }
        },
        lualine_z = {},
    },
    extensions = {}
}


local function ins_b(component)
    table.insert(config.sections.lualine_b, component)
end

local function ins_x(component)
    table.insert(config.sections.lualine_x, component)
end

ins_b {
    'branch',
}
ins_b {
    'diff',
    symbols = { added = ' ', modified = '柳', removed = ' ' }, -- why is the symbol for modified so weird
    diff_color = {
        added = { fg = colors.green },
        modified = { fg = colors.orange },
        removed = { fg = colors.red },
    },
}

ins_b {
    'diagnostics',
    symbols = { error = ' ', warn = ' ', info = ' ' },
    diagnostics_color = {
        color_error = { fg = colors.red },
        color_warn = { fg = colors.yellow },
        color_info = { fg = colors.cyan },
    },
}

ins_x {
    -- Lsp server name .
    function()
        local msg = 'No Active Lsp'
        local buf_ft = vim.api.nvim_buf_get_option(0, 'filetype')
        local clients = vim.lsp.get_active_clients()
        if next(clients) == nil then
            return msg
        end
        for _, client in ipairs(clients) do
            local filetypes = client.config.filetypes
            if filetypes and vim.fn.index(filetypes, buf_ft) ~= -1 then
                return client.name
            end
        end
        return msg
    end,
    icon = ' LSP:',
    color = { fg = colors.fg2, gui = 'bold' },
}

require('lualine').setup(config)

I've tried sourcing the config file on startup separately after requiring it, changing the order of my config, and looking for the highlight groups, but nothing has worked.