Can severe vitamin d and folic acid deficiency cause shoulder subluxation?

Depends on details. Many things are possible in life, so the answer to a "Can it happen" question is usually "Yes." Of course, that is not a very useful question nor answer. The real question is "How likely is it to happen?" In the US in 2019, there should not be people with severe enough nutritional deficiencies such that their joints, cartilage, and bones are not holding together under normal use conditions.