A lot of those USB powered lights actually need 5v 2A chargers, which many older adapters aren't capable of or could barely manage. So the light may work, but may be dimmer or end up slowly killing the adapter by trying to pull more power than it can really provide.
A good quality 5v 2A or higher adapter, like Anker, UGREEN, etc. is usually all you really need, not necessarily anything fancy with USB-PD support or multiple voltages.