Here is the feat, emphasis mine:
Poison Weapon ->
Requirements: You are wielding a piercing or slashing weapon and have a free hand
You apply a poison to the required weapon. If your next attack with that weapon before the end of your next turn hits and deals damage, it applies the effects of the poison, provided that poison can be delivered by contact or injury. If you critically fail the attack roll, the poison is wasted as normal.
(It also allows you to create simple poisons, which are not part of my question.)
The rules for injury poisons are as follows:
Injury: An injury poison is activated by applying it to a weapon, and it affects the target of the first Strike made using the poisoned weapon. If that Strike is a success and deals piercing or slashing damage, the target must attempt a saving throw against the poison. On a failed Strike, the target is unaffected, but the poison remains on the weapon and you can try again. On a critical failure, or if the Strike fails to deal slashing or piercing damage for some other reason, the poison is spent but the target is unaffected.
Without the feat, using poison seems pretty straightforward: you spend the listed number of actions to apply a poison, and it lasts seemingly indefinitely until you make a Strike and deal piercing or slashing damage (or critically fail a Strike).
But the rogue feat confuses me, specifically the italicized sentence. What happens if you fail to Strike someone by the end of your next turn? Is the poison wasted? Wouldn't that make someone who uses this feat worse at delivering poisons than someone who doesn't?