Most eBay sellers who come into these things from estate sales and such don't really know themselves. So the lack of attribution to the Browns isn't a significant condemnation by any means.
It might not be Browns... about a 20% chance in my mind that it's just a souvenir City Pennant. But the combination of colors, style of font and embroidery indicate a pretty high likelihood that it's a Browns pennant. You just never know for sure with these generic types. I tend to stay away from the "generics" for that reason.
But with this one, the leap of faith seems more like a bunny hop.