Not sure what to call this part so I'll call it a spring retainer, but it's part of the lift gate latch (same on both sides). There is a little plate that retains the spring on the side of the latch assembly towards the center. I took a picture of the broken one next to the good one and another of where the good one is in the assembly (with the spring a striker removed).
If anyone has an old liftgate latch laying around where this part is good PM me. Thanks everyone.