Unlinked Layer Duplication

When I duplicate a layer using Ctrl + D, the duplicated layer still references the same source item as the original.

This means that when I change certain properties on the duplicate, the same changes also appear on the original — as if both layers were still linked.

This is not the expected behaviour.

When duplicating a layer in the timeline, the result should be a fully independent duplicate that I can modify without affecting the original in any way.