I just got some awesome new art made for my podcast and had it done at 1400x1400 pixels. But when I create an .m4a file in Garageband, it outputs the art at a lower resolution. I want the art to be at full resolution.
I figured it out. A simple fix. When exporting a podcast to disk, there's an option to "Set artwork to recommended size for podcasts (300 x 300 pixels) when exporting." I had that checked, so I unchecked it and reexported.