I also learned a very hard lesson with red flannel from Joann's. I allows pre wash flannel because of shrinkage.
One of the colors with a plain red. Worst case of color bleeding I'd ever seen. All the fabric I'd washed was ruined.
I carried it back to the store to complain. They were even shocked at how bad it was. They refunded my money and I learned never to wash RED with anything. I actually have learned I no longer use red flannel from Joann's.