When I select part of an image and copy it (Ctrl J) to a new layer, it appears in the new layer with a white background instead of a transparent one. It used to provide a transparent background. I must have changed something, but I don't know what. I am using Elements 14.
I nthe layer panel, when you make a new layer, you typically, by default, will see the "little squares" to indicate it's a transpatent level.
I forced myself once to it set to "none" once for about a week-- I hated it that way.