No.
It’s just that adult life is less forgiving of ADHD symptoms.
As a kid they give you more of a pass because you’re a kid, they just assume kids get distracted, consumed by social life issues, or just “teen issues”. Maybe you fail one assignment but you pull a win off later that keeps your head above water thanks to averaging grades.
Now you move into a highly structured adult life where there’s far less forgiveness for failure to accomplish things by deadlines. Adult life doesn’t average your failure to pay bills or accomplish work your boss told you to do.
So yeah, ADHD is more stressful as an adult because there’s less forgiveness, less wiggle room.
JMO.