Why does my friend keep blacking out if her tolerance has grown

My female friend keeps blacking out after having less drinks than when she began drinking (about a year ago) she has been drinking more to the point that I’m concerned and built a noticeable tolerance (I’ve talked to her about this and told her multiple times that she should really stop drinking before she can’t go a day without it. Explained the mental and physical affects, stopped drinking around her most of the time, etc so pls don’t come at me). Almost everytime she drinks now, she tells us that she blacks out even if she doesn’t take much. I don’t understand how her tolerance has grown so high yet she is blacking out most times she drinks, again even if it’s two drinks. I thought it would be the other way around. I’m just here to ask if that’s an actual thing that happens when you’re becoming accustomed to alcohol, why would she be blacking out so much if her tolerance has grown so rapidly?