I'm not sure how but recently a few of the bombs ive been making have left non-moving high temp photons that dont decay, I thought this problem had been fixed a while ago?
I was trying out setting snows ctype to different things and i tried SING and set life to 90(dont even know if this did anything) set tmp to 999, as a result this happened
https://powdertoy.co.uk/Browse/View.html?ID=1187512
Usually there are a few that arent moving at all but you may have to reload a few times to get them