QGIS - what does these layer symbols mean

Question

I exported a polygon layer from R by means of st_write. In QGIS I find the layer in the geopackage file with symbol like this: enter image descript[layer ikon] here. There is a point, a line and polygon and I can't drag the layer from the browser to Layers window. The normal polygon layers have the polygon icon. What went wrong?

Answer 1

That means QGIS is not sure what sort of geometry your layer has, it is a generic geometry rather than a polygon layer. This should make no difference to how you use the layer.