Q.Wrinkly Thai chilies
I am growing a Thai chilli plant in a pot and it has begun producing a lot of fruit. Recently I’ve noticed the fruit starting to turn red but at the same time many look wrinkly and feel hollow. Does znyonr know why? Could it be under watering (I’ve been watering sparsely to correct my initial error of over watering. The leaves haven’t been wilting from under watering).
The first photo is of a large healthy looking fruit to contrast with the shriveled up looking ones.

The fruit will suffer from dehydration before the leaves do. Wilting leaves = severe dehydration of the plant. Don't wait for that sign before watering. Dig down an inch into the soil and if it is dry, it is time to water. Also, if nighttime temps are dropping into the 40s, chilies will have trouble. They like it hot!