I used to pull those hours most of my working life, going into an office so don't worry if your bosses are happy with your work and you're getting everything done then good for you. 99% of people going on about how stressed they are are doing it performatively as they think that's the sort of thing they should say, or it's self inflicted due to lack of planning or outside stressors.

If it's bothering you though and you want more to do because your bored (a common problem of being underworked) ask around if you can help anyone or ask your boss for more responsibilities. It most likely won't get you a payrise but will look good on your resume when you change jobs for a payrise.