The Skeptics Guide to the Universe podcast interviewed Grant Richey about this. He notes that some of the headlines were misleading, because the study did find that when flossing is performed by a dental hygienist on children, it has positive effect. So, a better encapsulation of the recent review is that improper flossing doesn't have any positive effect. On the other hand, its very unlikely to hurt you, unless you damage your gums in the process.

in case anyone wants a detailed review of the literature from before this study, Grant Richey did a blog post on it a few months ago: https://www.sciencebasedmedicine.org/may-the-floss-be-with-you/