Q.pumkin
I have been growing a giant pumkin
initially growth was fantastic then the early leaves lost colour and died but the rest of the plant thrived
a pumkin started to develop but after reaching the size of a large gratefruit stopped growing then started to become distorted and white tracks appeared
The plant still looks healthy. Why has Pumkin stopped growing?

The plants leaves may turn yellow from age, nutrient deficiency or infestation with pests or disease.
As the fruit ripens, the plant's older leaves at the base of the crown slowly die back. Although unsightly, this is a natural, harmless process. Cut off the dying leaves to help prevent the spread of rot and to improve air circulation around the plant.
As the fruit ripens, the plant's older leaves at the base of the crown slowly die back. Although unsightly, this is a natural, harmless process. Cut off the dying leaves to help prevent the spread of rot and to improve air circulation around the plant.
https://www.gardeningknowhow.com/edible/vegetables/squash/why-squash-leaves-turn-yellow.htm