I am familiar with the "-ridden" construction, e.g. "anxiety-ridden". I also know that "riddled with X" is possible. I recently saw the combination "ridden with X", which sounds off to me, but I'm not sure whether my intuition is a reliable guide here. Does "ridden with X" make sense, or is it an eggcorn?
It should be "ridden by anxiety", and not "ridden with anxiety". Maybe somebody misconstrued "anxiety-ridden" to mean "ridden with anxiety". I don't think that counts as an eggcorn, because it's incorrect back-formation, and not a misheard pronunciation.
You can google and find "anxiety-riddled" as well; that's an eggcorn. The "adjective-ridden" formation dates back to at least 1812 (here is "fear-ridden" from Google books) and "adjective-riddled" only appears much later.