Modern LED lights have a temperature regulation circuit that automatically steps down the brightness to prevent overheating. Once the temperature cools down a bit the light can be turned back to the maximum brightness. The 30 minutes runtime is a cumulative number that the battery can power the light at that setting, not a continuous runtime.
Every LED light with higher than 1000 lumens will step down within 30 seconds to a couple of minutes. A flashlight might have a longer continuous runtime if it uses multiple batteries to power multiple LEDs. But that's like bundling several lights together with each of them running at a lower brightness.
One might question the value of a high lumen (2000-4000 lumens) flashlight if it steps down after a minute. The truth is if you get an 800-1000 lumens flashlight. it will step down to an even lower brightness. And a burst of extremely high brightness, even not sustainable for long, is still useful in daily use.