Why does it say that leaderstats is not a valid member? I used waitforchild too.

Below is the script that's erroring.

local Players = game:GetService("Players")

local kickCommand = "!kick "

local function onOwnerChatted(player, message)
    if message:sub(1, kickCommand:len()):lower() == kickCommand:lower() then
        local name = message:sub(kickCommand:len() + 1)
        local playerToKick = Players:FindFirstChild(name)
        if playerToKick then
            playerToKick:Kick("Our moderators have determined that your behavior at SF Nuclear Lab has been in violation of our rules. Therefore, you are kicked from this game.")
        else

        end
    end
end

local function onPlayerAdded(player)
    if player.leaderstats.GVC2YDJ5.Value >= 1 then
        player.Chatted:Connect(function (...)
            onOwnerChatted(player, ...)
        end)
    end
end

for _, player in pairs(Players:GetPlayers()) do
    onPlayerAdded(player)
end
Players.PlayerAdded:Connect(onPlayerAdded)

Below is the leaderstats script.

local Players = game:GetService("Players")
local DataStoreService = game:GetService("DataStoreService")
local TestDataStore = DataStoreService:GetDataStore("emp43")

local data = {
    ["22XQ3SGH"] = 0,
    ["XTSAT8B7"] = 0,
    ["RVESMDXG"] = 0,
    ["8YHCNKMD"] = 0,
    ["D4VWKQF7"] = 0,
    ["ENB78YBQ"] = 0,
    ["GVC2YDJ5"] = 0,
    ["TKBRVCBQ"] = 0,
    ["6TU53T5F"] = 0,
    ["A79QBG5C"] = 0
}

Players.PlayerAdded:Connect(function(Player)
    local DataFromStore = nil

    local leaderstats = Instance.new("Folder")
    leaderstats.Name = "leaderstats"
    leaderstats.Parent = Player

    for name, value in pairs(data) do
        local new = Instance.new("NumberValue")
        new.Name = name
        new.Value = value
        new.Parent = leaderstats
    end

    local s, e = pcall(function()
        DataFromStore = TestDataStore:GetAsync("uid-" .. Player.UserId)
    end)

    if s then
        print("Getting Data For: " .. Player.Name)
        if DataFromStore then
            for name, value in pairs(DataFromStore) do
                Player.leaderstats[name].Value = value
            end
            print("Data Loaded For: " .. Player.Name)
        else
            print("Created New Data For: " .. Player.Name)
        end
    else 
        warn("Error Getting Data For: " .. Player.Name)
    end

    -- Check if banned.

    --if Player:WaitForChild("leaderstats").ENB78YBQ.Value >= 1 then
        --Player:Kick("Our moderators have determined that your behavior at SF Nuclear Lab has been in violation of our rules. Therefore, you are banned from this game.")
    --end
end)

Players.PlayerRemoving:Connect(function(Player)
    local DataForStore = {}

    for name, value in pairs(Player.leaderstats:GetChildren()) do
        DataForStore[value.Name] = value.Value
    end

    local success = pcall(TestDataStore.SetAsync, TestDataStore, "uid-" .. Player.UserId, DataForStore)

    if success then
        print("Successfully Saved Data For: " .. Player.Name)
    end
end)

game:BindToClose(function()
    for _, v in pairs(game.Players:GetPlayers()) do
        local success, errormessage = pcall(function()
            TestDataStore:SetAsync(v.UserId, data) -- define the data, since it's in a different scope
        end) 
    end
end)