ArcGIS Pro 3.5.0
In the main Definition Query tab in the layer properties, the layer name used in the spatial definition clause is not displayed. See red circle.

I'm wondering if the layer name could be included in the Geometry button in the spatial definition clause. There's not much space, so if the layer name gets truncated, then a tool tip should be available to display the full layer name.
I think that would be better than forcing the user to open the Spatial Clause Geometry dialog to see what layer is being used. And for what it's worth, that dialog doesn't do a very good job of showing what layer is used either. Spatial Definition Query — Highlight chosen layer