Access to patches to handle transparency of contourf

Hi there, I was trying to access patches that used to be accessible as children of the contourf handle. I wanted this access to adjust the transpareny which is very useful to create beautiful heatmaps with some other axes underneath - for example a map. But I noticed that in the latest release 2020b the children(h) returns an empty graphics handle and there seems to be no more access available to the patches generated by the contourf? Does anyone know how to get it back or is there any other way to adjust the transparency of colored patches generated by contourf?

Best