A simple typewriter example that allows for the previously set text to be overwritten without any problems.

Typewriter.lua

local textLabel = script.Parent

local lastUpdateTextThread = nil
local function updateText(newText: string)
	if lastUpdateTextThread then
		task.cancel(lastUpdateTextThread)
		lastUpdateTextThread = nil
	end
	
	lastUpdateTextThread = task.spawn(function()
		textLabel.MaxVisibleGraphemes = 0
		textLabel.Text = newText
		
		local totalGraphemes = utf8.len(newText)
		for i = 1,totalGraphemes do
			textLabel.MaxVisibleGraphemes = i
			task.wait(1/100)
		end
		textLabel.MaxVisibleGraphemes = -1
	end)
end

local function onCurrentTextChanged()
	updateText(textLabel:GetAttribute("CurrentText"))
end

textLabel:GetAttributeChangedSignal("CurrentText"):Connect(onCurrentTextChanged)
onCurrentTextChanged()