My character shouldn't move when I press the w,a,s & d keys when I'm holding shift

show some code. this depends totally how you handle input in your project

I don’t know if its a bug or something but
my player shouldn’t move while holding the movement keys (w,a,s,d) and (ctrl, shift, or alt).

I don’t know how to fix it, but I will try… Until then please help me by answering the question.

The description is a bit vague but it might be just this.