Diffusion film, like DCFix or similar.
Sticky can be slapped on the front glass and peeled off later if wanted.
Nonsticky would typically have to be wedged in between front glass and reflector.
More diffusey blurs the beam fairly smoothly, with the benefit of mixing colors from the beam if angular tint-shift would be an issue.
Less diffusey would just blur the hotspot into the spill, also mixing colors, but to a lesser extent.
I’ve got LuxPro lights which all use G3s, probably THE WORST LED chip out there as far as angular tint-shift. Even using one as a mule (no reflector or lens, just the nekkid LED) it throws blue light in front and yellow to the sides. But with some nice diffusey film, I get a nice even flood from all of them, great for using indoors to grubble around an attic, basement, etc.