Q.Basil Leaves Turned Wrinkly, Dry, And Are Yellowing. Sunburn? Underwatered? Fungus Issue?
Some of my basil leaves have curled up, had some dried up/crispy brown spots, and uneven yellowing. After some reading, it matches downy mildew but my plants don’t have any grey/black fuzziness on the bottom. Could I be underwatering and/or they are getting sunburned? Or do you think it is a fungus problem?

Certified GKH Gardening Expert
This is quite the opposite! Overwatering has, indeed, led to an infection. This is very common with Basil.
They will like to dry out pretty well between waterings. If they do not get a chance to dry down to about an inch or 2, completely, they will contract infections easily.
You can pick heavily infected leaves off and treat with natural fungicides, but it will return at some point. The best thing will be prevention.
Make sure to wash the container, thoroughly, before you plant again after harvest. This combined with using fresh soil will prevent another outbreak.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/garden-how-to/info/homemade-fungicide.htm
https://www.gardeningknowhow.com/garden-how-to/info/applying-bactericide-to-plants.htm
https://www.gardeningknowhow.com/edible/herbs/basil/basil-watering-tips.htm
https://www.gardeningknowhow.com/edible/herbs/basil/information-on-how-to-grow-basil-indoors.htm