Can the value editing of transparent pixels be disabled?

[Nerrel]

In 2.8.2 I made heavy use of the "value" mode for the paintbrush to do shading on layers with alpha channels.  This would let me shade only the actual painted areas of the layer without altering the transparent areas whatsoever.  In 2.10, Gimp now edits the transparency as well as the colored pixels, meaning that I can no longer use this brush to shade the objects on a given layer without also darkening the transparency around those objects in an unwanted way.

Is there any way to set the brush so that when in value mode it only alters the pixels that have been painted and not the transparency?

EDIT: I just discovered the "legacy" setting, which lets me get around this. I assume this is the only way to get what I'm looking for?
-Thanks