More information from testing:
The type 96 is also has the weird wake.
The newest Type 89 has no wake.
This a picture facing aft, immediately upon firing the forward tube with a Type 95 Mod1. The wake in front of the boat gradually develops, but the wake behind the sub appears immediately when the torp leaves the tube.
I can't show it in this picture but the wake is moving, but
not from the center. It is starting about the location of the red lines and moving in the direction of the arrow.
Just to leave no stone unturned. I loaded only the torpedo mod and fired from a German sub instead of the Japanese ones and got the same results. (which is what i expected)
Maybe the extra info may help.
Peabody