Yep , I just proved my theory right!!! After a very long time I finally did a test half-removing the chassis shafts of the rear suspension arms, straighten up the rear toe by putting some spacers between the arms and chassis , I did some tests and YES it's fixed!

(this is just temporary you can't run it like this for a long, the suspensions hardly work and did it just for the shake of the test)

Now the problem is that I don't know where to find adjustable rear suspension arms, or the STL file to 3D print a pair that has less inward toe! Can you help???

Before and after


Close up of the temporary mod