I think it doesn’t happen with every document but when I paste a layer (for instance a bitmap from the clipboard) into an artboard, the layer is pasted behind other layers and I have to manually bring it to front. My expectation would be (and I think that was the behavior in the past) that the layer is pasted to the front.
Hi Michael When you select a layer inside an artboard and then paste a new one, it will be pasted right above the layer you had selected, which can result in the pasted layer being behind other layers
To paste on top of all layers of an artboard select the artboard and then paste (with ⌘V or right-click → Paste here) and it will get pasted on top
Here’s a video that shows how selecting and pasting changes where the new layer is pasted, I hope it helps