Creepers, when taking fall damage, instantly explode. This has ruined so many hardcore worlds for me. This happens mostly in ravines, but in this case for me it happened in a desert temple, here's a video i edited (ps. it has loud music that i had while playing, but i had subtitles on so if it hissed, it would've displayed it, and it has happened multiple times in a ravine without a hiss so the song doesn't cover any hissing noises).

https://streamable.com/bo0vw7

I couldn't drag the file to the attachment since it was too big, so I uploaded it to streamable instead.