Decisive and Unbreakable need nerfs.
Go with scottjund's suggestions. Make DS infinite use, allow the timer to tick down but pause when the survivor is in chase. Instantly disable it if the survivor performs any actions. Repairing, Healing, sabotaging, unhooking, entering a locker, ect.
Give killers a notification it's active. Put a marker on the survivors health meter to let killers know a survivor has it. Doesn't have to show when it's active and not, just that they have the perk. Then make a visual indicator that a survivor has unbreakable primed. A unique crawling animation or something.
It's completely stupid that these perks are so damn impactful on games that you always have to play under the assumption that they have these 2 perks. Atleast with NOED and Devour Hope you can actively prevent it before it happens, but with these 2 you can't do anything until it's too late.