The article does not relate AI usage for homework to exam score drops.

It tries to link them together with no obvious cause and effect.

The score could have dropped due to worse environment at schools or kids who were stuck at home studying online and now in physical locations could not adapt fast enough (meaning, possibly just temporary drops). We do not yet have enough metrics gathered yet.

This type of article bashing AI for the root of any problems, I find it appalling without any evidence.

It's nothing but a conjecture.