Kat, a mononymous mommy blogger and former model, has racked up millions of views on videos that expose stark and alarming differences between clothes made for boys and girls.

“This is what Old Navy thinks your five-year-old little girl should be wearing to go down the slide,” she said in a recent video, holding up a pair of tiny denim shorts that resemble underwear instead of play clothes.

For comparison, she holds up a pair of much longer “quick-dry” khaki shorts created for boys the same age.

Licensed clinical psychologist Dr. Shahrzad Jalali agreed that uncomfortable pants can create unnecessary friction between a child and their environment, curbing learning and peer-bonding opportunities and creating stress and anxiety instead.

“A child who is thinking about whether her clothes will ride up, expose her or restrict her movement has less psychological freedom to simply move,” Dr. Jalali told The Post.

The California mental health expert added that freedom of movement supports exploration, which is “fundamental to developing motor competence, confidence and an embodied sense of ‘I can do this.'”