For me it wasn’t some boss or something. It was just some ridiculous precision platforming that couldn’t get past. I’m 45. My reaction times aren’t what they used to be. And the fact that you have to fight your shade every time made it just that much harder.
Ori and the Blind Forest also had some difficult precision platforming but the instant reload and no death penalty made it much easier to just try dozens of times until you get it.
Also, a baby-faced Meatloaf to really make you feel old