"Mental scars" refers to emotional or psychological damage that a person carries within themselves. It doesn't indicate physical injuries but rather emotional wounds that can impact their thoughts, emotions, and behaviors. Full definition
He is in his late 20s and bears mental scars from his time there. (theguardian.com)
I stressed that game would cut deep and leave mental scars and the effects would be permanent if things didn't change. (justarsenal.com)
I knew it was scary and that I would have a scar from my emergency c - section after our induction failed (I was induced two weeks early due to high risk pregnancy from gestational diabetes); but I didn't know it would leave me with mental scars. (doulasoflasvegas.com)