Hey there 👋
poly grow bags are made from durable plastic and are designed to be a low-cost alternative to nursery pots and other planting containers. They can be used in all the same applications as regular nursery pots and containers They should either come with a few drainage holes placed by the manufacturer, or you should have added some prior to planting. A lot of hydro stores sell them- but I personally agree that they retain too much moisture, and tend to stick to fabric bags for better wet/dry cycles.
Happy Growing 🌱