I just noticed there is difference between V4 and V5 with 2Dshadow rendering.

Try this:
-Open V4
-Add 2 video tracks with generated media (solid color).
-on first track, apply Track Motion with 2D shadow.

save veg file and open it on V5.
2D shadow is not the same (more accentuated in V5).

Not very annoying but good to know for those who open V4 project in V5.