Comment by hnburnsy

"Being held back" or grade retention is rare for high school students (teenagers), so rare that it is hard to find a study on it. RAND studied middle school and elementary school retention and found only some smallish negative effects.

https://www.rand.org/pubs/research_briefs/RB10025.html

Most middle\high school grade retention I see these days is self-imposed for an advantage in athletics; don't get me started.