I'm coming around to the idea that the 60 fps behavior was the intended behavior, and that's why each hand got an extra weapon slot
Probably, yeah. It only is a "bug" when you hit walls or corpses. Generally, durability mechanics feel like the developers wanted you to have to use more than one weapon, rather than just using a single weapon for most of the game.
For those that don't know the system, everything you have auto repairs to full durability, instantly and automatically, at every bonfire, as long as it isn't fully broken. Then you would need to do a paid repair back in town.
It was never similar to previous games. Honestly, durability should even exist in BB or DkS, because it doesn't fucking do anything other than occasionally make you use a repair shop. It's just... why? Such worthless stat pollution.
EDIT: The "Bug" does't do anything during normal play. Don't. Hit. Walls.