@kusuriya
Options can differ wildly, depending on where you live and what you want to sew. There are many businesses these days that sell deadstock and/or repurposed fabric. In Western Canada, we have
https://oursocialfabric.ca/
https://www.blenderzgarmentrecyclers.com/
Thankfully, we also have many brick-and-mortar stores, as well as a charity group that has a massive sale every April of deadstock, estates, and donated fabrics. That keeps me in projects for most of the year.