That's not even a stat question, it is a english question. It is an increase by 80% not to 80%
Statistics only come to play to figure out our new chances.
I'm not an expert either and your second option is definitly clearer than mine but I believe the % symbol doesn't have the meaning of percentage point.
It is better to make things easier for people to understand but people should also make the effort of properly reading even when it is not fully dumbed down. These are prepositions, so basic english not scientist jargon.
Im a high school maths teacher and that's what we're supposed to teach, % means percent, not percentage points. Maths always tries to have agreed-upon unambiguous definitions of things, precisely to avoid confusion.
"By 80 percentage points" means add 80 more points to a number of percentage points, so 5% becomes 85%. "By 80 percent" means add 80 percent of the current value.