It could be a design choice to give the character a certain look or to imply a tired or worn-out personality. Sometimes, it's just for visual interest and to make them stand out.
Maybe the character is sleep deprived or has been through a lot of stress.
Well, using cold compresses or eye creams specifically designed for this problem can make a difference. Also, staying hydrated and having a balanced diet can contribute to getting rid of those cartoon bags under your eyes.
Lack of sleep is a common cause. When you don't get enough rest, your body shows it, including with puffy eyes that look like cartoon bags.
Well, there could be various cartoons like that. Maybe in some comedies or fantasy ones for a funny or mysterious effect.
A cartoon dog with bags under eyes could mean that the dog is overworked or has been having trouble getting enough quality sleep. It could be a way for the artist to show a more vulnerable or worn-down side of the character.
Maybe the kid stayed up too late or had a rough night. That could cause bags under the eyes.
You can start by sketching some light shadows under the eyes. Make them kind of oval-shaped and add a bit of shading for depth.
Maybe it didn't get enough sleep. Just like us humans, animals in cartoons can look tired too.
Maybe he didn't get enough sleep. Or he could be stressed out from something.
It could be a way to show that they have a stressful and exhausting life as mobsters. Also, it adds to their rough and tough appearance.
It could be to show they're tired or stressed. Maybe they've been up all night or have a lot on their minds.