Frustration

I've been working on improving my squats and gaining depth for a long time. I used to work out with a friend who was always telling me that my squats are really bad/ wrong as well as my other lifts. Eventually I stopped lifting with them and joined cross fit, my coach at cross fit says I'm doing a great job improving on squats, but whenever my friend sees any videos they always say my knees are caving in and not at parallel etc, I find it really frustrating. I would think that a professional coach would know more than they do.