This happens all the time--recently, a podcast app was removed from the Play Store because it could be used to listen to content which didn't meet Play Store guidelines. The only way to fix it is to post about it and generate enough outrage that Google hears about it and can undo the ban.
When you say that's the only way to fix it, you are literally correct. There is no real ticket or support mechanism, no appeals process, nothing. The fastest way to raise an issue with Google is to email a journalist or hitup your twitter followers.
Apps being rejected was a talking point for the anti-trust investigations for Apple. I don't think Google is quite so famous for its rejections but they were part of that investigation for other abuse, hopefully any changes that come about will apply to them too.
Perhaps the FTC should have an office dedicated to overseeing policy enforcement for the largest store platforms. There could be a mechanism for saying "hi, I was banned by store X under policy Y but I believe my app was unfairly targeted because Z circumstance and Q other apps should all be treated equally here, including the first party app they're trying to protect..."
A better fix is barring by law tech companies that control important platforms from using those platforms to censor legal speech. It simply should be illegal for Google to down an app because it contains legal words that blaspheme against Google's California values.
This happens all the time--recently, a podcast app was removed from the Play Store because it could be used to listen to content which didn't meet Play Store guidelines. The only way to fix it is to post about it and generate enough outrage that Google hears about it and can undo the ban.