Unfortunately, the broader problem exists because it gets eyeballs. There are too many who will follow the doom and gloom because it helps keep them scared.

When you are on the home page for Medium when you see something in your feed you want less of, click the three dots "..." to the bottom right of the text blurb for an article and click on "show less like this". The same can be done in the app.

In the menu there is also a option listed as "refine recommendations" good stuff in there as well, even the option to clear your whole reading history for a fresh start it says. As well as muting specific writers.