Need help with filtering words for my nametag?

I wan't a nametag system like the game survivior but I wan't it to not allow you to use "[]" in the name?

what I have atm.

local RepStorage = game:GetService("ReplicatedStorage")
local Remote = RepStorage:WaitForChild("NametagCreatingEvent")

script.Parent.MouseButton1Click:Connect(function()
    if script.Parent.Parent.NameColor ~= "Nothing" and script.Parent.Parent.EnterNameBox.Text ~= "Enter name here" then 
        local NameChoice = script.Parent.Parent.EnterNameBox.Text
        if string.find(NameChoice, "[]") then
            script.Parent.Parent.EnterNameBox.Text = "Please don't try to imitate Moderation"
        else
            --Varibles--
            local PlayerName = game.Players.LocalPlayer.Name
            local ColorChoice = script.Parent.Parent.NameColor.Value
            --RemoteEvents--
            Remote:FireServer(NameChoice, ColorChoice)
            --Tweens
            wait(0.2)
            script.Parent.Parent.Parent.Backround:TweenPosition(UDim2.new(0.5,-200,1,0),"In","Quad",0.5,true)
        end
    end
end)