This is a subject on which you should think a little deeper. There is consistent research showing that being held back actually makes a student more likely to drop out before graduating high school, compared with equally low-performing students who are socially promoted, but does not necessarily make a huge difference in their skills.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726297/
From which:
"Over 40% of the students who repeated one previous grade and over half of students who repeated more than one grade left school during the year in which they turned 16, compared to only 15% of non-retained youths."
