It can be a relief to find that a pimple is gone, really, but such a nightmare to find it replaced with a deeper scar instead. Lesions, especially cysts, intensely damage the collagen with inflammation and cause this scarring.
People who have darker skin can have darkened spots inside of these scars, and those with lighter skin can have redness inside of them. Avoid exposing scars to sunlight, which can darken them and slow down their healing.