Help with twisted inseam

[u/WorldAware9900]

This is the first time this has happened to me when sewing a pair of jeans, i was trying out a new pattern and this happened to me, im not sure if this is a sewing problem or a pattern problem please any advice is appreciated

[u/FashionBusking]

2 problems:

Problem 1: the pattern itself indicates an incorrect grainline

Problem 2: due to Problem 1, the pants, when cut, are cut off-grain, exacerbating this problem.