There are scattered reports from people who take it and feel worse. Some don’t notice until they run out or forget to take it for a few days and realize their mood improves.

This happens with a lot of popular supplements. I don’t know how common it is, but it’s a thing that happens. There are proponents of every supplement who will tell you it’s perfectly safe and any negative effect is due to impurities or your imagination, but there are a lot of reports from people who believe it’s helping until they stop, and are surprised that they feel better without.