All players in a FFA deathmatch are able to see the hp bars of critically low hp players, regardless of whether they shot these players to reveal hp bars. This change was intended for 5v5 gameplay where stealing kills doesn’t matter, but it’s insanely game-breaking for deathmatch and already being abused by some players.
High mobility heroes like Tracer, Genji, Ball etc are the biggest culprits for abusing this change, by just hanging back and waiting to see players get to low hp before sniping a kill. It’s like giving everyone Sombra’s old Opportunist passive without any of her weaknesses to balance it out. This feature needs to be disabled for deathmatch.