This happened to me yesterday. I got the same Rejections Reason: "We noticed that your app provides the same feature set as other apps submitted to the App Store; it simply varies in content or language, which is considered a form of spam."
The SPAM REJECTION is supposed to be given to app when a developer makes a copy of one of their already existing apps and then makes trivial changes to it to try to get additional copies into the App Store in order to get more downloads.
This IS NOT what I did. My app was completely written from scratch by me and unlike anything I had written before.
What I think happened is the name I gave it was similar to the name of another app written by someone else and their app was known as being spam in the past. The reviewer must have assumed mine was just a copy that they made.
The reviewer obviously did not even bother to try my app before labeling it spam which is frustrating.
I posted a reply to their rejection and I've been waiting for a day to hear back.
I believe there is a way to appeal but I hope I don't have to jump through all those hoops just because Apple has lazy reviewers.
Here is a link to the appeal page.
https://developer.apple.com/contact/request/app-review/appeal/
It's frustrating that Apple hires lazy reviewers and a hundred hours of my time could be wasted because they can't spend 15 minutes trying out the app before falsely labeling it spam.