How do you make it so players can't stand up from PlatformStand by pressing backspace?

I know this is possible, since Deathrun 2 has it.

I already tried this:

plr = game.Players.LocalPlayer
mouse = plr:GetMouse()

mouse.KeyDown:connect(function(key)
	if key:byte() == 8 then
		wait(3)
		plr.Character.Humanoid.PlatformStand = true
	end	
end)

But all it does is create a sort of super jump button. Anyways, I could use some help.

I've been disliked too much for answering. This is my last answer. I hope this helps!

plr = game.Players.LocalPlayer
plr.Character.Humanoid.PlatformStand = false
mouse = plr:GetMouse()

mouse.KeyDown:connect(function(key)
    if key:lower():byte() == 8 and plr.Character.Humanoid.PlatformStand == false then
      for i = 0, 1 do
wait(3)
        plr.Character.Humanoid.PlatformStand = true
plr.Character.Humanoid.PlatformStand = false
end
    end 
end)

As you can see, waits not that reliable. Instead I mixed it up a bit changing to check if the players platformstand is false, and if it is, it runs a for loop that waits 3 seconds to run. For loops are much more reliable then waits, waits glitch out alot and are buggy.