[SOLVED BY MYSELF] For some reason this only works with really high values (around 1000+)?

I decided to make the comments i had wrote into an Answer.

What you are doing atm is checking if the delta between two axis is higher than the root of walkspeed. this could fail multiways and be very inaccurate. first of all delta axis could be negative for example 5 - 500, which should ve kicked the player but didnt next you are doing the root of maxWalkSpeed which grants the player a lots room where he can cheat but not be detected. like say maxwalkspeed is 16 which would 256 in which you compare, meaning player could go up to 256 without being detected. at max i would do 16 *2 which 32, which leaves enough room to prevent false positives.

Instead of doing delta of each axis you should be doing Magnitude of said Positions, Magnitude of the subtraction of two positions is the distance between them.

so at the end we get this

local requireed = require(script.Parent)
local maxWalkSpeed = requireed.maxWalkSpeed
local multi = 2

game.Players.PlayerAdded:Connect:Function(plr)
	plr.CharacterAdded:Connect(function(char)
	local HPR = char.HumanoidRootPart
	local KickText = "kicked"

	while true do wait(.2)
		local pos1 = HPR.Position
		wait(1)
		local pos2 = HPR.Position
		if (pos1- pos2).Magnitude > maxWalkSpeed * multi then
      		 	plr:Kick(KickText)
		end
	end)
end)

but this still can lead to false positives, for example if a player falls into the void or falls from great heights, his speed will massively increase and will pass the Magnitude check. The counter this you can leave out checking Y coordinate but this leaves the player again room to cheat in the Y direction.