On the extension-closed property for the subcategory $\text{Tr}({\mathrm{\Omega }}^2(\mathrm{m}\mathrm{o}\mathrm{d}-A))$

We present a monomial quiver algebra $A$ having the property that the subcategory $\text{Tr}({\mathrm{\Omega }}^2(\mathrm{m}\mathrm{o}\mathrm{d}-A))$ is not extension-closed. This answers a question raised by Idun Reiten.