It doesn't seem like knee valgus is an actual issue. People discuss it and say it's something you should fix. It is generally a sign of poor glute, especially poor side / upper glute, strength. Working on your side glutes apparently decreases knee valgus. I've never heard of anybody getting injured from knee valgus. The same thing goes for posterior pelvic tilt during various compound leg exercises. I've broken so many rules when it comes to injury prevention with certain exercises that I'm naturally always skeptical when someone tells me an exercise can injure me. I started lifting in 2013.

I also have a theory that the adductor magnus contributes towards knee valgus. The adductor magnus is both a hip adductor and hip extensor. It functions like a hamstring. The thing is, with the way the muscle fibers are oriented and the attachment points on the femur (I'm personally just going off of images I saw online.), it looks like when it contracts, you can't really isolate its hip extension function from its hip adduction function. The so-called hamstring portion of the adductor magnus still attaches to the side of the femur rather than underneath it, so it should still contribute towards hip adduction. The side glutes are going to oppose the hip adduction caused by the adductor magnus. This is just my theory, but I'm not the only one who thinks the adductor magnus plays a role in knee valgus.