Paper cuttings made by 17th-century schoolgirls discovered beneath floorboards

IIRC paper was mainly made from linen or cotton back then and it actually was less likely to turn yellow than more modern wood pulp paper (which was only invented in the early 1800s)

Paper made from textile is slightly alkaline and contains very little lignin which is highly reactive and causes paper to turn yellow over time. Pulp paper is also more acidic which also makes it more susceptible to degradation.