Not if you don’t accept the premise of ‘reception’ classes & arbitrary ‘baseline scores’ predicated on a date which necessarily introduces bias due to its relationship with a child’s birthdate. Instead introduce mixed age classrooms & observation as the method of determining a development trajectory

These are the results for the low scoring children. Month of birth ought not to be a predictor of numeracy or lack of it.

Umsurprisingly the data for multiplication tables testing displayed a similar pattern. These are the results of the high scoring children 21-25.

Yes

The causal mechanism is simply the cut-off-date eligibility rule for entry into the state education system. DfE chooses 1 September and inevitably relatively older September born children are then more successful than their relatively younger August born classmates.

This third chart counts children for whom the phonics test has been disapplied, presumably because they're destined for failure.

It's systemic discrimation because the system, which is owned by the Department for Education, selects children by month-of-birth for failure in the realm of literacy.

The first chart counts children by month of birth who meet the expected standard.

This second chart counts the children who are still working towards meeting the expected standard.