i got a solution
i have solved this by looking for a possible problem
i have concluded that roblox seems to add all the meshes textures together.
that means the edges seem to bump into each other leading to having each others influences.
the solution is simply scaling down the size of the object (In UV editing) with the strange line or just make the vertices not touch the outer bounds of the image thats supposed to be the spot where the color will be inputed later on in roblox studio.
before
after
