I left a battlescape to go repair my DST at a friendly station. While repairing I read, in red, at the top of the screen, “you killed so-and-so (griefing)”. Is this a joke or did I really do something bad?
Chances are you accidentally did some damage to a friendly, likely with a mine or another explosive, and when they died you had done enough damage to be credited for the kill. It’s nothing to worry about unless you do it repeatedly on purpose.