"Give me a realistic smooth motion blur script that applies blur when the player rotates their camera in first person. It doesn't apply on movement, only camera rotation"

-- Local Script 
local Players = game:GetService("Players")
local TweenService = game:GetService("TweenService")

local player = Players.LocalPlayer
local camera = workspace.CurrentCamera
local blur = Instance.new("BlurEffect")
blur.Parent = workspace.CurrentCamera
blur.Size = 0

local function updateBlur()
    local lastCFrame = camera.CFrame
    while true do
        wait()
        local deltaCFrame = lastCFrame:ToObjectSpace(camera.CFrame)
        local rotationAmount = math.abs(deltaCFrame.Y)
        local targetBlurSize = math.min(rotationAmount * 100, 20)
        local tweenInfo = TweenInfo.new(0.1, Enum.EasingStyle.Sine, Enum.EasingDirection.Out)
        local tween = TweenService:Create(blur, tweenInfo, {Size = targetBlurSize})
        tween:Play()
        lastCFrame = camera.CFrame
    end
end

player.CharacterAdded:Connect(function(character)
    local humanoid = character:WaitForChild("Humanoid")
    humanoid.CameraOffset = Vector3.new(0, 1.5, 0)
    camera.CameraSubject = humanoid
    camera.CameraType = Enum.CameraType.Custom
    updateBlur()
end)