Q.Why Do My Vegetables Have Big Leaves And Small Roots Or Fruit?
L have grown huge gardens for 60 years. As a child that’s was our main source of food.i have grown a few vegetables on my balcony the last few years. This year, from purchased bags of soil, my Carrots and Beets have big leaves but no substantial roots. The carrot tops are over a foot high and the thin little carrots are a couple of inches long. They should be thicker and at least 4 inches long. The beets are the size of a matchstick. I have never seen this before.

Certified GKH Gardening Expert
Are you growing them in the bag or in a container? You may need a larger container for good root growth. This article is about raised beds, but it shows the depth vegetables need.
Also, are your veggies getting full sun on the patio? That can be an issue. Here is more:
https://www.gardeningknowhow.com/edible/vegetables/vgen/raised-bed-soil-depth.htm
https://www.gardeningknowhow.com/special/containers/growing-vegetables-in-buckets.htm