I'm researching for a future novel. Google Gemini gave me this:

4. Non-Clinical & Environmental Factors

• English as a Second / Additional Language (ELL/ESL): Math concepts and recess games translate across language barriers much more easily than reading and writing fluency. A child developing English proficiency might be held back if her reading levels lag behind grade-level standards.

• Chronic Absence or Educational Gaps: Missing extended periods of school due to illness, family moves, or medical conditions during kindergarten or 1st grade can leave severe gaps in foundational reading instruction, even if her innate reasoning (math) and social intelligence (recess) remain strong.

• Emotional / Environmental Stressors: High situational anxiety, trauma, or major life changes can impair working memory specifically needed for reading comprehension and testing, without impairing her social outlet during unstructured playground time.

Summary Perspective

If a school recommends holding a child back under these circumstances, it is usually because her reading benchmark scores (which become vital for all subjects in 3rd grade) are below level, or her executive skills (task initiation, sitting still for sustained reading) are lagging.