This happens in every depression study: Placebo effect is extremely strong for depression.

You can even collect depressed people, do nothing at all, and when you survey them 6 months later the average scores will improve. This is because depression is, on average, an aberrant condition and the average patient will tend to revert toward the mean.

However, psychedelic studies have a bigger problem: Psychedelics trigger false feelings of amazement and wonder, feeling like something magical has happened. This is like turbo placebo when you tell people that it’s a depression treatment. Maybe that’s a valuable therapeutic effect, or maybe not. There’s a lot to explore, but from all the studies I’ve read I’m not as bullish on mushrooms for depression as the headlines would indicate.

Not defending that - some times just knowing you are trying to better yourself helps make things seem better.

As far as I know antidepressants and even pain killers are the most susceptible to placebo effect.