The dietary supplement industry is a
multibillion dollar industry and is largely unregulated. It's not just false claims of efficacy, but often you will find impure products, unsafe or outright fake supplements that end up on shelves of even well known local pharmacies.
In the US the industry is estimated to be worth $159 billion.
"Supplement overdosing accounted for
20% of liver damage and hepatotoxicity in the US in 2017 and that number is likely higher now.
Over 50,000 adverse events are reported to the FDA every year, and that is likely lower than those which occur, because people don't know
that you can report supplements."
So at the very least, make sure the manufacturer is legit and also read up on any studies, side effects and interactions like with anything else.