Podcast cover art size specifications
It's important that your artwork image has the right size in pixel and the right file size.
Most listening apps will refuse wrongly sized artwork images which can directly impact service performance.
The specifications are suitable for Podkite, Apple Podcasts, Google Podcasts, Spotify, etc.
Ideally, the artwork image should be square and between 1400 x 1400 and 3000 x 3000 pixels.
The file size should be ideally below 512KB.
Use tools like TinyPNG to compress your image if you have troubles reducing the file size.