Apologies for this new bug, and thanks for reporting it. The new GeoGraphics still rasterizes the output in some projections, and it is not doing a proper job in this case, because it is not taking into account that the output will have a large image size. I can offer two alternative workarounds for it:
1) Prevent rasterization. Try this:
GeoGraphics["World", GeoProjection -> "Mollweide", ImageSize -> 1600, Method -> {"VectorMapRasterize" -> False}]
2) Intercept the rasterization process and increase the image size. Try this:
AppendTo[System`GeoStylingDump`$VectorRasterizeOptions, ImageSize -> 1600];
GeoGraphics["World", GeoProjection -> "Mollweide", ImageSize -> 1600]
The quality is then better in either case:
