Apple can fail, reject, or remove your podcast from Apple Podcasts for a variety of reasons.
Here are some common issues that cause podcasts to be rejected by iTunes:
No episode published yet. You need to publish at least one episode with valid audio/video to be accepted by iTunes.
The language set in the feed doesn’t match the one used.
Artwork with incorrect specs. Apple requires Podcast feeds contain artwork that is a minimum size of 1400 x 1400 pixels and a maximum size of 3000 x 3000 pixels, 72 dpi, in JPEG or PNG format with appropriate file extensions (.jpg, .png), and in the RGB colorspace.
Explicit language without setting the <explicit> tag to yes, explicit, or true.
Content that could be construed as racist, misogynist, or homophobic.
Explicit or self-censored explicit language in titles, subtitles, or descriptions.
References to illegal drugs, profanity, or violence in the title, description, artwork, or episodes.
Content depicting graphic sex, violence, gore, illegal drugs, or hate themes.
Third-party content or trademarks without legal authorization or usage rights.
Content considered spam: recently Apple has been rejecting podcasts containing keywords in the title and author tags. They want these fields to be reserved strictly for the title and author, without adding keywords or ancillary information.
You can test your podcast’s technical aspects with the following steps which are recommended by Apple:
Open iTunes, choose File > Subscribe to Podcast, enter your RSS feed URL in the text box, then click OK. If you can successfully download and play the episode, then your podcast is working and you can submit it to Apple Podcasts.
If you are not sure why Apple has rejected your podcast, you can email Apple Support for more information. Go to https://itunespartner.apple.com/en/podcasts/overview click the 'Contact Us' link at the bottom of the page.