Apple’s rendering engine shrinks every image to 1400 × 1400 px on the front page and to 1400 × 1400 px in the app’s thumbnail slot. If you supply a 800 × 800 image, the server stretches and blurs it. Stick to the spec: 1400 × 1400, 1:1 ratio, 72 dpi, and a final file size under 1 MB.

Contrast is the next killer. Apple’s algorithm masks edges when the foreground‑to‑background contrast dips below 3:1. A soft gradient or a semi‑transparent background will get smoothed out. Design with hard, high‑contrast edges—dark text on a light backdrop or vice versa. Test it on a low‑resolution phone screen; if the text blurs, bump the contrast.

Compression is a silent sabotage. Apple recompresses JPEGs at 70‑80 % quality by default. If you’re already saving at 50 % or lower, the artifacting will multiply. Export your art as a 90 % JPEG (or a PNG if you need transparency) and keep the file size ≤900 kB. Use a lossless PNG when you need crisp lines or a transparent background—Apple keeps that intact.

Workflow tip: open your final file in the Apple Podcasts Connect preview. Hover over the thumbnail; if you see a pixelated outline or fuzzy text, you’re already doomed. Keep a single master file in your assets folder and re‑export it each time you tweak. That way you always know the version that will actually hit the players.