since you asked for it i'll explain to you... when you see that people do emotes before fighting and the others aren't trying to kill immediately the invader, it means that there's currently a duel between the invader and the host (or one of his phantoms). in your case you attacked me from behind while i was duelling a friend of the host without asking to yourself why the others were idle...

nice net bro, your ghost range is incredible

did you know how to duel? it seems not...

ha yeah it seemed fun, had to try it

a felllow DangItJm fan!

https://youtube.com/clip/Ugkx_X3bgBM91hHnAQVbVNE2_J0Sb83Vk7gE