A word meaning "a student who is repeating a class or grade"

Is there a word in English for a student who is repeating a grade at school or a (university) student who hasn't completed a mandatory course successfully the first time and is retaking the class?

I already heard the term holdback used for "repeater."

hold back: (idiomatic) to delay, especially in school. He's a year older than his classmates because he was held back in second grade (Your Dictionary)

Middle School Holdbacks Banned from Athletic Participation

Last week, the Kentucky Board of Education approved a new statewide rule recommended by the Kentucky High School Athletic Association that, beginning in the 2015-2016 school year, middle school students who repeat a grade for any reason won't be able to play on a school athletic team in the year they are repeating. (BlueGrassPreps)

repeater (n.)

Education (originally and chiefly U.S.). A student who undertakes a grade or course again.

1909 Cleveland Public Schools Ann. Rep. 32 Dr. Ayres affirms that every sixth child in the elementary schools of American cities of size is a ‘repeater’.

2004 Washington Post (Nexis) 12 May a1 Many of the repeaters had failed English, which students must pass before they become 10th-graders. OED

A student enrolled in a class or course for a second or subsequent time. m-w

In the recovery system at my school, I teach the ninth-grade repeaters English 9 every day for the first and second quarters. If they pass the class during the first and second quarters, they are eligible to take English 10 during the third and fourth quarters. If they pass both English 9 and 10 through the system, they will have recovered two English credits in one year. Gary Hughes; Powerful Language for Reluctant Learners (2020)

Two of my classes had several repeaters in them, and I wouldn't have known this fact; except the teacher made it public knowledge because he couldn't control them at the time. My thoughts were, "God why are you punishing me? First, you did not allow me to become gifted and now you have me in a class with misfits?" Jane Green; Life (2017)