Heat. Almost all modern fixtures count as "enclosed" - and most LED bulbs, if you look closely on the case, aren't rated for "enclosed or recessed" use. Basic

Heat. Almost all modern fixtures count as "enclosed" - and most LED bulbs, if you look closely on the case, aren't rated for "enclosed or recessed" use. Basically, they're fine, if they're upright in a table lamp or so. Most modern fixtures are recessed, and the bulbs are "upside down" - so the heat builds up in the base of them, where the power electronics are, and simply fries them. There's a typical, handwaving, "For each 10C above design temperature, the lifetime halves" curve you can apply, and those power electronics are running way above design temperature in "almost all modern uses." So they die quickly. An enclosed rated bulb is worth trying, if you can find one that does what you want. But good luck. They're cheap consumer devices at this point, built to a price point.