Without physically evaluating her I can't be sure if this is a «preferred position» for her (i.e. if she already has underlying
muscular or skeletal asymmetries) but too much time in this position will likely lead to shortened muscles on the right side of her body (your left when you're looking at her), which can
then make it harder for her to use her right hand, to lift her head in Tummy Time, to turn to see objects on her right side, to turn toward sounds or touch sensations on her right side, to roll, to use both
arms equally to assume the hands and knees position for crawling, to sit upright.
It should be noted that I have more
muscular arms than probably average but I would say that if you have anything other than super skinny
arms then either size up (way up) or avoid this top all together.