This has been a bug I've noticed a lot since 2.0 dropped. It would sometimes happen in older version of the game, but no where near as often. Despite only using guns with the Pax mods, enemies I down will often straight up die. This isn't due to accidentally double tapping either: a single shot...
For the most part, the system of having main quest progression gradually unlock side quests works well and ensures you don't run out of content to do during waiting periods between missions. However, the " I Fought the Law" and "The Beast in Me" feel like they have their triggers reversed...
This problem is especially noticeable in the badlands where it feels like I'm getting constant pop-in. Extremely prevalent in vehicles or otherwise moving at high speeds. Problem persists even after a complete clean install, ini reset, etc.