Though I can’t say for sure without comparison pictures from when you were younger, it looks like you’re receding. That said, it could, (depending on your starting point), be a mature hairline if it doesn’t progress any further, but that would require that you had a very high hairline throughout your life. Again, earlier pics could reveal this.
If you compare to earlier pictures and the difference isn’t drastic, keep an eye on it and take pictures every 3 months. If the hairline moves or the crown thins then you’ve got male pattern baldness. If you want answers sooner you may want to go see a doctor.