Idk Why its a thing but when using viper if u kill someone the teammate doesnt see the viper for like 2 secs thats an advantage coz u cant see them when they kill someone they can backstab u and instant kill u Who Agrees to changed this Viper Invs after kill for 2 secs thing
Thats literally a purchaseable upgrade.. (3rd one I believe) You will receive invisibility upon getting a kill, it's not a bug lol