If you are looking to download this or similar sound effects for your own projects, several reputable platforms offer royalty-free libraries:
Freesound and Pixabay are major global platforms where users share a wide variety of sounds, including military and impact effects.
The "grenade-plonk" is a common used in gaming and film to represent the specific metallic "thud" or "clink" of a grenade launcher firing or a grenade bouncing off a hard surface.