They’re removing ads from the site based on content standards they have agreed to with the advertisers. They’re not censoring anything and have only notified you of the changes you would need to make if you want to keep their business. You are not owed revenue from Google or anyone else.
Is it a problem that so much of the Internet, including your site, “depends” on corporate advertising? Yes. Is that censorship? No. You are free to find your own sponsors.