I don't know if my son's experience is relevant but I'll share it.
DS6's reading comprehension level as privately tested is at least 4/5 grade level. The reading comprehension work at school involves writing sentences in response to questions about a passage. He has dysgraphia so this is really challenging. So he might work at grade level when writing is involved and then later work above grade level when oral responses are given. So the grade level work is more a handwriting exercise for him to practice staying on the line, making neat letters, spacing, and punctuation.
I didn't look up your previous post but maybe the school's assessment involved writing?
