Cheap lights
I clicked the above magicshine link to Amazon, then browsed other lights.

This "1000 lumen" external battery light (plus a tail light!) for $32: Link
The reviews show an extreme hotspot in the middle of the beam.
And a reviewer said the beam gets dimmer as the battery runs down. Just about every LED light uses a "voltage regulator" so that the beam stays bright until the battery is quite low. For $32, they have to cut every corner, on electronics inside, on cheap connectors, on sketchy batteries that you might not want to leave unattended while charging. And the batteries might stop holding a charge fairly soon.