If your pelvis shifts laterally during a squat, this is explained by an asymmetrical lack of hip or ankle mobility, or by a deficit in gluteal stability, which you must correct with targeted mobility and strengthening exercises.

noli's read

A cross-sectional observational study published in ISU ReD confirms that individuals exhibiting lateral pelvic deviation indeed have a significant reduction in ankle flexion mobility and hip asymmetries. Furthermore, observational biomechanics research referenced by the PMC portal shows an alteration in gluteal muscle activation on the side of the deviation. The link between hip shift and a localized deficit in mobility or strength is therefore scientifically sound. On the other hand, the idea that this shift necessarily increases the risk of physical discomfort or hinders performance requires nuance. A systematic review of cohorts published in Physical Therapy in Sport shows that slight asymmetries in strength or movement are commonplace in healthy athletes and are poor predictors of injury risk. The obligation to systematically correct every minor weight shift is therefore more of an expert opinion, as an asymmetrical squat may simply be a natural and comfortable anatomical adaptation.

the sources

No named source held this one up — that absence is part of the verdict.