There seem to be certain things that can push you through a very aggressive chrome web store review process. Under most circumstances there is no review whatsoever, you're just waiting for your extension .crx file to get pushed to their CDN (and maybe scanned automatically for trivial classes of exploits?)
If you get hit with a DMCA claim (fraudulent or otherwise) that'll put a manual review flag on your account for a while. You can tell because pushing an update or new extension takes over a day vs the standard ~20-60 minutes. The manual review can and will just reject you for no reason without much explanation, but it seems to be easy to just bypass the review.
The 60 minutes delay is completely artificial, it is only there in case you change your mind. If you use the API, extensions are published immediately. Whatever automated scanning takes place there, it's very quick.
If you get hit with a DMCA claim (fraudulent or otherwise) that'll put a manual review flag on your account for a while. You can tell because pushing an update or new extension takes over a day vs the standard ~20-60 minutes. The manual review can and will just reject you for no reason without much explanation, but it seems to be easy to just bypass the review.