http://www.bbcweb3hytmzhn5d532owbu6oqadra5z3ar726vq5kgwwn6aucdccrad.onion/future/article/20220321-what-happened-to-the-worlds-ozone-hole
Despite the Montreal Protocol's overall success, there have been setbacks. In 2018, for example, the concentration of CFC-11, banned since 2010, was found to not be coming down as quickly as was expected, suggesting undeclared emissions were coming from somewhere.