why can't I review anything anymore?

Make sure the app you are attempting to review is in your purchase history?

View your purchase history for the App Store and other Apple media services - Apple Support

There is no such thing as a ghost ban. A repeated violation of the Terms of Use will result in your account being deleted and you will not be able to use it at all for any purpose. There is nothing wrong with a negative review and those are expected in the App Store where apps can also be rated as a 1. A negative review can be done without vulgar language, threats, or rude behavior, by simply stating the facts and your experience. For some reason, the former seems to be acceptable on Social Media sites, so users think that is how we should be communicating with each other.

I see negative reviews on apps in the App Store all the time and they are very helpful.

When you submit a review, the Developer can either respond back to you directly in the review where you will be notified, or if the review contained offensive content or violated Apple Terms and Conditions, the Developer can notify Apple to have them look at it to determine if there is a violation and you will not be notified if it is removed.

If you see a review that contains offensive material, spam, or other content that violates Apple’s Terms and Conditions, use the Report a Concern option under the review in App Store Connect instead of replying to the review. The user who wrote the review will not be notified that you reported a concern.

Ratings, reviews, and responses - App Store - Apple Developer

I have no idea what your review said, but you can clearly see that there are apps with poor reviews and it is encouraged that users write those to let others know of their experience. You can also report a concern directly to Apple for any quality issues with an app by going to reportaproblem.apple.com. I problem with an app that is not resolved by the Developer or if you think the app is a scam, you should definitely be reporting it there.