@barrons - nope, still bunky. Nobody has ever been able to prove any causal relationship between casual sex and depression/mental health.
If you read that Psychology Today article, you’ll see that most results are 1) correlational and 2) mixed. Many researchers have found some kind of relationship between depression and casual sex, but many researchers have also found no association. And it’s very difficult to do causal inference without doing an experiment, which would be unethical (and impossible) in this case, so we don’t know what comes first or whether there are third variables. For all we know, depression could cause casual sex - young people who are depressed may seek out casual relationships as a way to self-medicate. People with poor mental health do all sorts of destructive things to try to feel better.
Interestingly, some of the more nuanced studies have found that it has lots to do with your outlook on sex, too - the article has more about that.