for maximum benefit, buy .edu email addresses for 3 dollars ( google buy .edu email , or just get one on ebay), sign it, and have amazon prime yearly for about 6 bucks.
Point is to increase visibility (because $$$ from referral clicks).
My working theory based on the timing of this is that Prime Student sign-ups that typically surge during the "Back to School" period because of textbook orders/school supplies were way below expectations which they (Amazon) are blaming on lack of awareness rather than a trending increase in eBook rentals/purchases/piracy (as a result of classes moving online during the last two school years), better pricing at other retailers or availability issues.