A general point? Grapes are just not suited to growing indoors. They are totally hardy plants which need outdoor conditions. Can you give more information on your growing techniques?

When I bought my Pixie Grapes they were listed as being not over-winter "outdoor" grapes. They are known for being grown in containers and producing several times a year only getting a couple feet tall at the most.

They are grown on a windowsill that gets southern light this time of year. There are also grow lights around that they probably get supplemental light from, from my citrus trees. Watering every 3-5 days. Fertilizing is done lightly every month or so with a "berry" type of fertilizer.

Not familiar with them, but...I notice a heater in the background, what is the humidity level?

It's actually a fan haha I can see how it looks like a heater though. I have a humidifier in with my plants as well. I usually keep it around 40-50% humidity because of my other plants in the room.

Floral has hit the primary issue.......grapes are not intended as indoor plants. While 'Pixie' is a very compact variety that can be easily grown in a container and bears early and frequently, it is still an outdoor vine!! It is just a cultivar of Vitis vinifera and is fully root hardy to zone 3. It should be dormant at this time or very nearly so.

The only concern for them over winter would be the size of the container. Small containers can freeze in cold climates and that can damage root systems. So they do need some protection......either by bringing into a cool location (below 45F but above freezing) or by burying the container into a spot in the garden. The plant needs to go dormant - that is its natural intent - and preventing this from happening by keeping in 'bright' light and continuing to fertilize, etc., will eventually shorten its lifespan.

And when the weather will accommodate it, the container should be outside. Grapes want full sun. And no matter how many grow lights you have or how bright your window sill, you will not come close to providing the intensity of light it needs to flourish indoors.

Yes, I understand that it is just a dwarf variety of an actual full size grape plant. I understand that it needs to go dormant. My question was not originally about growing conditions or what can I do to make it grow amazingly perfect indoors but of a leaf issue I've noticed on my one particular plant.....

Crispy leaves are very likely a sign that it wants to go dormant - let it. And put it in a much cooler environment to do so.