Scratch

Do you have a little project that shows the distortion?---the gif you provided a link to does not contain enough information to debug the problem.


One common cause of distorted sprites are directions that are not quite 90, 180, -90, or 0 degrees.  An angle of 0.1 degrees can result in distortion, though not exactly what you show.

Yes, that certainly shows the distortion on my Mac.
The 45 by 18 rectangle gets badly distorted when rotated 90 degrees.

Changing it to a plain rectangle still has the same problem.
Changing the color doesn't change the problem.
Moving the rotation center doesn't fix it, nor does moving the rectangle in the edit window or moving the sprite location.

This looks like definite bug in the rotation code---perhaps someone converting floats to integers by truncating rather than rounding or using floor, since the right half of the resulting image comes out ok, but the left half is missing pixels.

Scratch team, you have a genuine, replicatable bug here!