The xp bar won't go away

[Dssall2]

So I have it works so that when you get xp green bar is filled, but when you leveled up the bar does not go back, here’s the script, it is local, self-filling works but retracting it does not

local player = game:GetService("Players").LocalPlayer

local exp = player.Data.Exp
local requiredExp = player.Data.RequiredExp
local lvl = player.Data.Level

exp.Changed:Connect(function(changed)
	if changed then
		script.Parent.BackgroundFrame.ExpFrame:TweenSize(UDim2.new(exp.Value / requiredExp.Value, 0, 1.310, 0))
		if exp.Value == 0 then
			print("1")
			script.Parent.BackgroundFrame.ExpFrame:TweenSize(UDim2.new(exp.Value, 0, 1.310, 0))
		end
	end
end)

while wait() do
	script.Parent.ExpLabel.Text = exp.Value.. "/".. requiredExp.Value
end

[DasKairo (Cairo)]

Because you arent checking if the Exp is greater than the required Exp, if you want it simply, just check if the exp is greater or equal to the required exp, and if so subtract the exp by the required exp, like so:

-- Server:
if exp.Value >= requiredExp.Value then -- if exp is greater than required
    exp.Value -= requiredExp.Value -- subtract exp with required
    print("Level Up")
end
-- Client:
script.Parent.BackgroundFrame.ExpFrame:TweenSize(UDim2.new(exp.Value / requiredExp.Value, 0, 1.310, 0))

Handle this on the Server first of all, because the Client cannot make these types of changes for the Server, plus its safer, unless you already have that kind of system

You should remove the while loop, instead use the .Changed Event.