I am using QGIS 3.18.1.
I am working on a map around Alaska. I added a world basemap, then added DEM and finally drew a few polygon shapefiles on top.
I then tried to find a projection more appropriate for that area and chose NAD83(2011) / Alaska Albers (EPSG:6393).
The world basemap and DEM for transformed nicely but I am not sure about the polygon shapefiles. Shouldn't the top and bottom lines be rounded off to follow the longitude? You can notice on the second image that the top of the DEM now curves while the shapefile remained straight.
I have tried exporting the layer as EPSG:6393 and adding it back. But still the same result. Any pointers?